Digital Currency
DCJPY (tentative name)White Paper
November 2021

Digital Currency ForumTable of Contents

3

Executive summary6

1. About the Digital Currency DCJPY (tentative name)

6[1] Overview

12[2] Platform

22[3] UI of the digital currency DCJPY

24 2. Value Provided by Digital Currency
26 Appendix
27 Glossary

About the name of the Digital Currency

2

The digital currency being developed by the Digital
Currency Forum is tentatively called as “DCJPY”.
The Forum will continue considering how its digitalcurrency should be entitled.

Executive summary
Recently, there has been a significant increase in social demand for economic digitalization and digital transformation (“DX”). This is due to recent innovation of digitaltechnologies, rapid popularization of smartphones and other digital devices, drastic
increase in the volume of data, and expanding possibilities for data utilization.
Furthermore, the spread of Covid-19 infections disease has prompted digitalization
efforts from the perspective of developing an infrastructure that can sustain economic and social activities while avoiding physical contact of humans.
Increasingly sophisticated and complex societal demands are also working towards
accelerating the application of digital technologies and DX. The policy goals forsustainability and decarbonization are increasing the need to track and ensure
traceability through digital technologies, including carbon foot-printing. New
assets class such as Non-Fungible Token (“NFT”) and security token (“ST”) are also
emerging through digital technologies. Furthermore, the social issue of regional
revitalization is also leading to expectations for the application of digital technology.
To drive a DX and link digital technologies to economic growth and increased social
welfare, there is a payment and settlement infrastructure that can be driven by
private-sector-led innovation. It must be secure, reliable, fast, inexpensive, widely
available, and able to meet a variety of needs.
To achieve this aim, it is important to proactively utilize digital technology in thepayment and settlement infrastructure itself. Currently, such efforts are accelerating worldwide. For example, BigTechs, which are giant tech companies, are entering
the digital payments. These also include the emergence of crypto assets, “stablecoins” based on new digital technologies and aiming to stabilize their value, and theCentral Bank Digital Currency (“CBDC”) initiatives.
One of the most promising technologies is Blockchain or distributed ledger
technology (“DLT”). These were originally introduced along with crypto assets astechnologies to prevent alteration of ledgers and double transfers. More recently,
they are expected to create a programmable infrastructure that can be used towrite “smart contracts” tailored to individual business needs. These functions are
attracting attention not only for payment settlements, but also for the creation of
new investment products, and as an infrastructure that enables trading of various
digital contents such as digital art and music.

3

Considering recent advances in digital technology and the demands of the economy
and society, the Digital Currency Forum has been actively studying the ideal form ofdigital payment and settlement infrastructure, which could contribute to enhancing
people’s welfare and to fostering the developments of the economic society. The
forum has decided to develop a yen-denominated digital currency with a two-tiered
structure that incorporates new technologies, and to move forward with efforts
to put it into practical daily usage. This digital currency will be tentatively called
DCJPY. The name of the digital currency will be further discussed and officially beannounced at the earliest opportunity by the Forum.
The “Common Area” of the DCJPY digital currency will be a structure shared by all
the digital currencies issued under the scheme and will contain information on value
and will be in charge of them for issuance and burn. This area is expected to ensure“interoperability” between digital currencies.
The “Business Process Area” of the digital currency DCJPY can be programmed tomeet various business needs (i.e., programmability), and will be responsible for the
distribution of the digital currency. In this way, it will be possible to respond to avariety of business needs, such as linking payments and settlements with logistics
and commercial distribution, and simultaneous delivery of goods and services andfund settlement payments (Delivery versus Payment, “DvP”).
There are various options for stabilizing the value of such digital currencies in Japanese Yen. For example, a method of storing an amount equivalent to the balance ina safe and liquid asset in a bankruptcy-remote manner could be considered. Basedon the idea that the infrastructure for such a digital currency should be realized assoon as possible, the Digital Currency Forum has decided to first consider a scheme
in which the digital currencies are issued by banks as their liabilities, similar todeposits. This is based on the fact that the safety and soundness of bank deposits
are secured by bank regulation, supervision and deposit insurance. Individuals andfirms use bank deposits as payment instruments without worrying much about
their soundness. Therefore, the Forum considered that the digital currencies issued
by banks could be the fastest way to incorporate digital technologies in payment
infrastructure.

4

Currently, so-called “stabled coins,” which are designed to stabilize their value,
are seen as a promising means of payment. However, there is a global concern
about regulatory gap among them and bank deposits. In this regard, the scheme of“turning bank deposits into digital currency DCJPY” will be able to overcome suchproblems. It also avoids the risk that digital currency will erode bank deposits andreduce financial intermediation through banks. The Digital Currency Forum is not
limiting itself to this scheme and will continue to explore and study other options.
The Digital Currency Forum also envisions that digital currency, DCJPY, will beable to connect organically with other digital platforms. In other words, the Forumaims to realize a form of “Digital Payment as a Service,” in which various economic
activities and businesses can add payment and settlement functions as one of theirwide-ranging services by incorporating the scheme of digital currency in accordancewith their own business needs. The Digital Currency Forum will post future updates
on a regular basis.

5Part 1

About the Digital Currency DCJPY(tentative name)[1] Overview
This chapter describes the characteristics of DCJPY, the Two-tiered Digital Currency
that the Digital Currency Forum is working on, and the platform which is the mechanism making it usable.
The platform itself, which handles DCJPY, is not necessarily limited to yen-denominated digital currencies, and the Forum believes that a wide range of applications
including cross-border instruments are possible, although addressing money
laundering and other relevant issues are yet to be explored.

a. Features of the Digital Currency “DCJPY”
This chapter describes the characteristics of DCJPY, the Two-tiered Digital Currency
that the Digital Currency Forum is working on, and the platform which is the mechanism making it usable.
The platform itself, which handles DCJPY, is not necessarily limited to yen-denominated digital currencies, and the Forum believes that a wide range of applications
including cross-border instruments are possible, although addressing money
laundering and other relevant issues are yet to be explored.

b. Nature of the digital currency DCJPY
It is assumed that the digital currency DCJPY will be issued by commercial banks as
their liabilities, which are similar to bank deposits.
The minimum currency unit of DCJPY is one Japanese Yen. The Digital Currency
Forum will continue to consider how to handle cases where there is a need forsmaller currency settlement of funds in less than a unit.
It is assumed that DCJPY will not bear interests and will be insured by deposit
insurance.
The act of transferring DCJPY to another user based on a user’s request is assumed
to be regarded as an exchange act by a private commercial bank as an issuer. The
exchange of DCJPY between users in the Business Process Area is assumed tobe “the act of a user instructing the issuer bank to transfer DCJPY in the Common
Area. In this way, the series of operations recorded in the Business Process Area ispositioned as a record of the transmission of instructions, and the transfer of DCJPY
itself is based on the record of DCJPY account balances in the Common Area.

6

c. Digital Currency DCJPY Scope of Offer
For the time being, the users of the digital currency DCJPY are assumed to becorporations and individuals within Japan, and the places where DCJPY can be used
are also assumed to be within Japan.
In the near future, The Digital Currency Forum would like to profoundly research andmay consider the possibility of use by non-residents and use outside Japan.

d. “Mint”, “Transfer”, and “Burn” of the digital currency DCJPY
The digital currency, DCJPY, will be minted by withdrawing deposit from the user’sbank account and posting the equivalent amount of DCJPY to the digital currency
account opened by the user on the digital currency platform.
DCJPY will be transferred from a user’s account to another user’s account by (i)direct transfer instructions in the Common Area as described below, or (ii) receiving
transfer instructions in the Business Process Area as described below, which transfer instructions are automatically transmitted to the Common Area.
DCJPY is also burned in the form of a reduction in the account balance of the digitalcurrency upon the user’s request and the delivery of an equivalent amount of cash
or deposit to the user.
(i.e., At the initial stage, users who wish to exchange DCJPY for cash are required to
do so via bank deposits.)7

e. Common Area and Business Process Area
To issue, transfer, and burn the digital currency DCJPY, the Digital Currency Forumhas defined and established two-tiered area, so called “Common Area “ and “Business Process Area”, and envision a mechanism to link them. This is also called the“Two-tiered Digital Currency Platform.
The functions of the Common Area and the Business Process Area are as follows.

Company B
Company B
CompanyA

Business
Process
Area

CompanyC

CompanyA

CompanyC

Company D
Company D
User

1

Transfer ofgoods and rights

User

2 Coin transfer
instruction

1 The transfer of goods and rights is recorded in
the ledger of the Business Process Area.

One Time Public Key
via electronic payment
service provider

2 The message of the coin transfer instruction isrecorded in the ledger of the Business Process
Area as a transfer log.
3 The transfer of coins is recorded in the ledger of
the Common Area.

User

3 Transfer of coins

CommonArea

User

Bank B

Bank ABank CBank D

Figure 1-1: Common Area and Business Process Area in Two-tiered Digital Currency

8f. Common Area
The Common Area provides functions for managing the ledger, which records thebalance of the digital currency DCJPY, and related operations, as well as mechanisms for linking with the ledger systems of commercial banks when they issue
digital currency.
To open a digital currency account, a user must first have a bank deposit accountwith a commercial bank that manages digital currency accounts. Upon receiving arequest for the issuance of DCJPY from the user, the bank will debit the user’s bankaccount and credit the same amount of DCJPY to the balance of the user’s Common
Area account.
The DCJPY issued in this way can be transferred to other users’ accounts in the
Common Area. Currently, this service is limited to transfers between digitalcurrency accounts managed by the same bank, and the Digital Currency Forum
will continue to study proactively the possibility of transfer service among digitalcurrency accounts managed by different banks, with a view to more practical dailycommercial usage.
Functions such as issuance and burn of DCJPY using the Common Area, checking thebalance of the account for the Common Area, and designating the Business Process
Area are expected to be performed through the common application, “Common App”
for DCJPY or through applications provided by individual commercial banks.
The Common Area will also contain an account for the Business Process Area, inwhich will be linked to the exchange of DCJPY through the Business Process Area
as described below. Users will be able to transfer their account balances between
the Common Area account and the Business Process Area Sync account within the
Common Area.

g. Business Process Area
The Business Process Area is an area where programs can be programable andwritten to meet a variety of service needs. This makes it possible, for example, touse DCJPY for payment settlement in a way that links it to the flow of goods.
Specifically, within the Common Area, DCJPY is transferred from the user’s Common
Area account to the Business Process Area Sync Account. The Business Process
Area Account is created in the form of a link to this account. When the balance of
the Business Process Area (the Business Process Area Coin) in the Business Process
Area Account is transferred by a user operation or smart contract, etc., DCJPY in theBusiness Process Sync Account in the Common Area will be transferred between
users, reflecting the transfer in the Business Process Area.
In this case, the record of the transfer in the Business Process Area can be regarded
as the record of the instruction for the transfer of DCJPY in the Business Process
Sync Account that exists in the Common Area (the transfer of digital currency itself
is conducted in the Common Area).

9

Business
Process
Area (1)Company H(Administrator)

User X

User Y

User XBusiness Process
Area(1) Account(Transfer log)

User Y
Business Process
Area(1) Account(Transfer log)

If a process in either the
Common Area or the Business
Process Area is not completed,
The Digital Currency will not betransferred.

CommonArea

User XBusiness Process
Area(1) Sync AccountUser Y
Business Process
Area(1) Sync AccountUser X
Common Area AccountUser Y
Common Area AccountBank ABank B

Account holder

Account holder

Figure 1-2: Linkage between the Business Process Area and the Common Area

By introducing such a mechanism, the transfer of DCJPY linked to the transfer ofgoods, services, and digital assets can be realized using smart contracts and othermethods. Also, by linking the Common Area with the Business Process Area, it
becomes easier to transfer digital currency between different Business Process
Areas.
For example, as shown in the following diagram (Figure 1.3), when multiple
economic spheres exist, such as Peer to Peer (“P2P”) transactions between power
generators and consumers via a dedicated platform such as an electricity trading
platform, and security token (“ST”) transactions, each transaction has conventionallyrequired payment settlement by means such as interbank transfer only.
The platform envisioned by the Digital Currency Forum will allow for flexible use
within the platform. For example, using DCJPY obtained through power trading topurchase ST in a flexible timely manner within the platform.

10Electric Power Business Process Area

STO Business Process Area

Retail Business
Process Areae-money
Business
Process Area

CommonArea

BankBank AccountBank AccountFigure 1-3: World view realized by Business Process Area and Common Area

11

Bank AccountBank Account・・・[1] Platform
In building the Two-tiered Digital Currency infrastructure, it is important that thebalances in the Common Area and the balances in the Business Process Area arelinked real time. A promising technology to achieve this is so called “blockchain, or
distributed ledger technology” (thereafter “DLT”).
As mentioned above, a digital currency platform has a two-tiered structure consisting of the Common Area managed by commercial banks, which issue, transfer, andburn the digital currency DCJPY, and Business Process Areas managed by users
such as companies and individuals, which provides various services and values. The
technical features of each are introduced as below.

Business
Process
Area

CommonArea

User XBusiness Process
Area AccountBusiness Process
Area AccountUser X (Bank A)

User Y (Bank A)

Business Process
Area Sync AccountBusiness Process
Area Sync AccountCommon Area
Account

Common Area
Account

Issuer(Bank)
Figure 1-4: Two-tiered Digital Currency Platform

12

User YBank A

a. The Common Area
a-1. Common Area Outline
It is a structure using blockchain to issue, transfer, and burn DCJPY bycommercial banks. In addition, the use of smart contracts makes it possible toimplement complex business flows. Furthermore, interoperability is ensured,and data can be mutually exchanged with other blockchains on timely manner.
As the following explanation, the features of the Common Area from four
perspectives will be described.

a-2. Features of the Common Area
Feature 1. Compatibility of Management Control and Confidentiality
The Common Area consists of a permission-based blockchain technology. Thus,
the entities which can process or refer data on the blockchain are limited to
specific nodes.
In the digital currency platform that handles DCJPY, it is temporarily assumed
that all nodes in the Common Area will be managed and operated by commercial banks. These banks will be responsible for processing and referencing
the database in the Common Area. In addition, cryptography will be used toensure data confidentiality and privacy protection. The Common Area accountassociated with a user will be individually managed by commercial banks andwill not be shared by DLT. Therefore, it is not possible to inquire the accountbalances of users at other commercial banks.

Feature 2. Byzantine Fault Tolerance
A consensus algorithm based on PBFT (Practical Byzantine Fault Tolerance)
has been implemented to determine the correctness of the data in the Common
Area.
The blockchain will continue to function even if (N-1)/3 or fewer of the N
specific nodes that can verify the correctness of a block and be involved in thedetermination of a new block are incorrect or faulty (this property is called
Byzantine Fault Tolerance).
The validators responsible for block generation can be added or removed
during the operation with the consent of a majority of all validators.

Feature 3. Tamper-Resistant
Each block of the blockchain that constitutes the Common Area has the hashvalue of the previous block. To tamper with a block that has been determinedin the past, everything from the block in question to the latest block must be
tampered within a consistent manner. Also, to tamper with a block, it is necessary to have enough nodes as accomplices to outperform the BFT described in
section 2. This is quite difficult, and the tamper-resistance is extremely high.

13Feature 4: Transparency of Transactions
In the Common Area, as a function of distributed ledger technology (“DLT”),
it is possible to verify the state of all nodes, thus ensuring transparency oftransactions. On the other hand, by utilizing cryptographic theory, it is possible
to verify the authenticity of DCJPY transfers without knowing the contents ofthe transactions.

a-3. Functions of the Common Area
DCJPY issued by each bank based on instructions from the user will be issued to the“Common Area account” in the user’s Common Area, which is linked to the user’sbank account.
In the Common Area, the commercial bank is the primary operator. The main operations that can be performed in the Common Area are as follows(1) Create a digital currency DCJPY account(2) Retrieve list of digital currency accounts, retrieve and update attributes(3) Obtain balance of digital currency account(4) Issue digital currency(5) Set and obtain permission to remit digital currency(6) Remit digital currency(7) Burn digital currency(8) Inquire Transaction and inquiry list
Furthermore, DCJPY transfer linked to transactions using Business Process Areas
will also be possible. (See below;)14

b. Business Process Area
The Business Process Area is a domain in which allows a wide range of businesses
to incorporate services and functions while retaining the features of DLT describedin the Common Area section.
In the Business Process Area, users can develop and implement their own smart
contracts. For example, they can issue their own “tokens” and incorporate various
functions as smart contracts. Such smart contracts can also be executed fromoutside the digital currency platform through APIs. This makes it possible to integrate the digital currency platform with existing systems.
Companies and local governments are expected to be the main administrators of
the Business Process Area, while businesses and individuals as their customers arealso expected to operate them. As with the Common Area, the main operations thatcan be performed in the Business Process Area are as follows(1) Create an account in a Business Process Area
(2) Get the list of accounts in the Business Process Area, and get/update their attributes(3) Obtain the balance of the Business Process Area account(4) Issue the Business Process Area Coins(5) Set and obtain transfer permission for the Business Process Area Coins(6) Transfer the Business Process Area Coins(7) Burn the Business Process Area Coins(8) Transaction inquiry and list inquiry
To send transfer instructions from the Business Process Area to the Common Area,
an interoperability package is introduced. This makes it possible to instruct DCJPY
transfer from the Business Process Area to the Common Area.

15

c. Flow from Creation of a Digital Currency Account to Transfer
The following describes the image of how the Common Area and the Business
Process Area function in conjunction, looking at the flow (“sequence flow model”)
from the creation of a digital currency account in the Common Area to the transfer ofdigital currency through transfer instructions from the Business Process Area.
For the sake of technical accuracy, the DCJPY on the Common Area is referred toas the “Common Area Coin” and the token for transfer instruction, which is shadowof the DCJPY on the Business Process Area, is referred to as the “Business Process
Area Coin”

Step 1
User “X” and User “Y” have deposit accounts at a Bank A. Upon receiving an application from each user, Bank A creates the Common Area Account linked to eachuser’s bank account, respectively.

Business
Process
Area

CommonArea

User X (Bank A)

User Y (Bank A)

Common Area
Account

Common Area
Account

add

Issuer(Bank)
Figure 1-5: Creating a Common Area Account

16

add

Bank AStep 2Furthermore, upon receiving a request from each user, the commercial bank will
create a Business Process Area Sync Account in the Common Area. In addition,
upon request from the user, the Business Process Area Account for each user’s
Business Process Area Coins will also be created in the Business Process Area by
the company or municipality.

Business
Process
Area

CommonArea

User X

User Y

Business Process
Area AccountBusiness Process
Area AccountUser X (Bank A)

User Y (Bank A)

Business Process
Area Sync AccountBusiness Process
Area Sync AccountCommon Area
Account

Common Area
Account

add

Issuer(Bank)

add

Bank A

Figure 1-6: Creating an account for a Common Area

Step 3
Based on the instruction from each user, Bank A issues digital currency to the Common Area Accounts of User X and User Y (this DCJPY is called a Common Area Coin).

Business
Process
Area

CommonArea

User X

User Y

Business Process
Area AccountBusiness Process
Area AccountUser X (Bank A)

User Y (Bank A)

Business Process
Area Sync AccountBusiness Process
Area Sync AccountCommon Area
Account

Common Area
Account

mint

Issuer(Bank)

17

Figure 1-7: Issuing a digital currency

mintBank AStep 4
Based on the instruction from User X, Bank A transfers the digital currency in User
X’s Common Area Account to the Business Process Area Sync Account. And then,the balance of the Common Area Coin in the Business Process Area Sync Accountand the Business Process Area Coin in the Business Process Area Account will be
synchronized simultaneously.

User XBusiness
Process
Area

CommonArea

User Y

Business Process
Area AccountBusiness Process
Area AccountUser X (Bank A)

User Y (Bank A)

Business Process
Area Sync AccountBusiness Process
Area Sync AccountCommon Area
Account

Common Area
Account

Issuer(Bank)

Bank A

Figure 1-8: Transferring the Common Area Coin to the Business Process Area Sync Account andsynchronization of the Business Process Area Coin Balance

Step 5
When User X transfers the Business Process Area Coin to User Y in the Business Process
Area, this information is transmitted to the Common Area as a transfer instruction,and the Common Area Coin are transferred from User X’s Business Process Area Sync
Account to User Y’s Business Process Area Sync Account within the Common Area.

Business
Process
Area

User X

Issuer(Bank)

18

Business Process
Area Accountvia electronic payment
service provider
Send

CommonArea

User Y

Business Process
Area AccountSynchronize(Coin transfer instruction)

User X (Bank A)

User Y (Bank A)

Business Process
Area Sync AccountBusiness Process
Area Sync AccountCommon Area
Account

Common Area
Account

Bank A

Figure 1-9: Transfer of digital currency with instructions from the Business Process Area

As shown in the above the step 5 process, the transfer of the Business Process
Area Coin and the synchronization of the Common Area Coin balance are considered
finalities (i.e., finalization of settlement). The transfer of the Business Process
Area Coins in the Business Process Area constitutes the instruction to transfer the
Common Area Coin in the Common Area.

d. Custom Contracts
The ability to deploy user-developed programs (custom contracts) in the Business
Process Area is one of the features of digital currency platforms.
When transmitting the transfer instructions described in the previous section, various processes can be linked by executing them synchronously with the transmissionof the transfer instructions created by the user.
How this is achieved is explained below.
In the Business Process Area, a custom contract called “Custom Transfer” to add
various elements to the transfer of the Business Process Area Coin (“Transfer”) is
implemented. It can be called Custom Transfer by setting the contract address of
Custom Transfer in the Common Area contract.
Custom Transfer allows us to add various functions to the transfer of additive coins,and here is an example to give us an idea of how it works (the oracle in the explanation is the mechanism that receives information from outside the blockchain).

Example 1
Linking supply ratio and price to solve the food loss problem
Custom Transfer Processing Details
1.
2.
3.

Refer to the Key (product name) and Value (supply ratio) registered in Oracle*
Calculate the reduction rate from the supply rate of the product in 1
Execute Transfer with the result of 2

Using this process, a system that adjusts the balance between supply anddemand by increasing the reduction ratio (i.e., selling at a lower price) for
products that are in excess and sending a smaller amount of money based on
the supply ratio of the product obtained from the outside in 1.
Example 2: Delivery versus Payment (“DvP”) in Non-Fungible Token (“NFT”)
transactions*The digital currency platform implements an “oracle” function that imports external data into the blockchain. An
oracle is a generic term for a mechanism that receives information from outside the blockchain and reflects it insmart contracts. Systems that send information to oracles are not limited to software; there are also use cases
where information is sent from hardware such as Internet of Things (“IoT”) devices.

19

DvP in NFT transactions is realized by a custom contract that performs NFT transfers in conjunction with Transfer.
Process of Custom Transfer: What Custom Transfer does
1.
2.

Refer to the Token ID (bytes32) of the NFT registered in the oracle
Transfer of the NFT whose Token ID is specified in 1 is also performed asa result of the transfer of the Business Process Area Coin

Using this process, it is possible to send money and receive NFTs in the same transaction. This enables so-called DvP, where the transfer of assets and settlement are
executed simultaneously, and if either of parties fails, the transaction itself becomes
invalid.

20

e. FAQs
The Digital Currency Forum has received questions at the sessions and other events.
Here are some of them with answers.

21

Q1

As a technical element, when the transfer cannot take place unless the Business
Process Area and the Common Area are synchronized, will one transaction that has
been transferred be unwound, or will the transfer not occur in the first place?

A1

If either the transfer of the Business Process Area Coin in the Business Process
Area or the transfer of the Common Area Coin in the Common Area fails, thetransaction will not be completed, and the balance will not change.

Q2

What controls are in place to ensure that the payment instructions in the Business
Process Area match the transfers in the Common Area?

A2

Transfer instructions in the Business Process Area are linked to the status in the
Common Area. The balance of the Common Area and the balance of each Business
Process Area (lock balance) are managed separately, and the synchronization of thepayment instruction in the Business Process Area and the digital currency transfer
in the Common Area is achieved by checking both.

Q3

Will the transfer of the Business Process Area Coin and the transfer of the Common
Area Coin be synchronized in "real time”, or will some parts be handled in batch?

A3

Transfer transactions are processed in blocks, so there could be a slight delay inthe order of block creation time. This is a quasi-real time system in the sense that
there is a delay of a few seconds rather than completely simultaneous.

Q4

Please tell us about the range of data that can be stored in the Business Process
Area, including restrictions on size, security, and confidentiality control.
Is it possible to store sensitive information, or is it possible to store only the key
and control the data itself by storing it in a side chain or another DB?

A4

The data handled by the platform should be organized and used in the transactions
between the parties to be shared.
It is also possible to share only the key (e.g., a hash that can be verified after thefact) to objectively guarantee authenticity, but not to share the data. Since the datalayout varies from company to company, the information management functions
will be implemented outside the platform.

Q5

Where will the program be written? Can it be written in the token, outside the token,
or some other variation? Can the program be corrected or modified later?

A5

The program (contract) is written and shared in the blockchain. It also has
upgradability features such as version control.

Q6

Can this system be stopped in case of some fatal bug or mistake? If so, what are
the steps (authority control) and scope?

A6

Since the interfaces that accept requests, such as transfers in transactions are
implemented outside the platform, it is possible to stop them by stopping theacceptance of requests.
(Depends on the make of the system outside the platform)

[3] UI of the digital currency DCJPY
When users use the digital currency DCJPY, they will do so through the application.
The Common Area application will be a bank-connected app that issues the digitalcurrency, and multiple Business Process Areas (corporate applications) will beconnected to it.

EnterpriseApp

IssuingBankEnterpriseApp

CommonAppEnterpriseApp

As a digital currency
management application

EnterpriseApp

Figure 1-10: Application Connection Imagea. The Common Area Application
The Common Area application will be a digital currency management application.
It is assumed that users will use the common specifications regardless of whether
they are corporations or individuals. The main operations that can be performed in
the Common Area application are as follows.
• Create a digital currency account• Issue Digital Currency (the Common Area Coin) from commercial bank fiat deposits• Transfer the Common Area Coin from the Common Area Account to
the Business Process Area Sync Account• Burn Digital Currency (the Common Area Coin) to commercial bank fiat deposits• Send and receive the Common Area Coin to other users• Search for nicknames of users within the same commercial bank account22

Figure 1-11: The Common Area application operation screen (reference implementation)
Issue Digital Currency, the “Common Area Coin” from commercial bank fiat deposits

b. Business Process Area Application (corporate applications)
Business Process Area applications (corporate applications) are developed andreleased by companies and municipalities that provide services in the businessprocess of the digital currency platform according to their requirements. The entitythat operates the application in the Business Process Area is the business or individual who is a customer of the service provided in the Business Process Area.

23

Part 2

Value Provided by Digital Currency
The digital currency DCJPY is expected to (1) stabilize value in Yen by taking theform of banks’ liabilities, (2) ensure interoperability through the Common Area, and(3) meet various needs through Business Process Areas. Also, a brief mention of thevalue that Digital Currency creates.

a. Foster innovation, reduce costs, improve efficiency
As a digital currency issued by a commercial bank, DCJPY avoids the problem ofcompetition with bank deposits. This will also encourage private-sector innovationand contribute to cost reduction and efficiency improvement.
Various companies and municipalities can use this digital currency platform to think
about how they can add value to it.
For example, they can digitize paperwork such as purchase orders and invoices
between companies and use smart contracts in the Business Process Area of digitalcurrency to liberalize manual settlements, thereby reducing costs and improving
administrative efficiency. Furthermore, if the entire supply chain in the manufacturing industry and the delivery chain in the distribution industry can be settled in
DCJPY, it is possible to improve the efficiency of supply chain management (SCM)
and the productivity of the entire business model. In addition, the use of DCJPY as
a payment method will contribute to cost savings in hard cash handling, change
preparation, hard cash storage, hard cash transportation, and security.

b. Cooperation among economic zones
by ensuring interoperability
Until now, digital payment methods such as e-money provided by private companies
have often been limited in interoperability as a result of their aim to expand theirown economic sphere and promote customer loyalty within the economic sphere. In
contrast, the DCJPY digital currency ensures interoperability through the Common
Area, allowing it to be used beyond the economic sphere established by each company. This will increase convenience for customers, and for companies, the digitalcurrency platform will function as an infrastructure for building new services to beoffered across economic spheres.
Furthermore, by incorporating DCJPY functions into some of the applications
developed by the company and linking these to the Common Area, digital payment
settlement services can be provided as if they were part of the company’s own
wide-ranging services in the form of “Digital Payment as a Service”. In this way, it
will be possible to provide digital payment services as if they were part of a broader
range of services.

24

c. Improving people’s economic welfare
Blockchain and distributed ledger technology (DLT) are no longer limited to therealm of cryptographic assets but are now actively being used to create newfinancial products such as security token (ST) and new assets such as non-fungible
tokens (NFT). It is also expected to be used as a technology to ensure traceability of
products and primary commodities. For example, with the growing global interest
in Environmental, Social, and Governance (“ESG”) and The Sustainable Development
Goals (“SDGs”), it is becoming increasingly important to trace and prove the energy
used to manufacture products, and there are high expectations for blockchain anddistributed ledger technology in this regard.
In this way, the use of blockchain and distributed ledger technology in the payment
and settlement of transactions for goods, services, and assets that use blockchain
and distributed ledger technology is a competitive advantage from the perspectiveof using smart contracts to coordinate the two. From this point of view, the digitalcurrency DCJPY is expected to become a useful payment instrument for efficiently
conducting transactions of new assets, and ESG/SDGs-conscious transactions.

25

Appendix

26

Glossary
1. RolesDefinition

Word

Common Area

Roles

Business Process Area

An entity with a specific function
Operators who are responsible for preparing the Common
Area, providers, validators, and issuer as administrators ofdigital currency platforms.

Administrator

ProviderThe entity responsible forcreating the token

The entity that is responsible for preparing theBusiness Process Area andcreating the token.

Validator

An entity that synchronizes
the Common Area Coinwith the Business Process
Area Coin and transfers
the Common Area Coin

Entities that are responsible for transferring theBusiness Process Area
Coin

IssuerEntities responsible forthe issuance and burn ofdigital currency(Not present in the Business Process Area)

User

Digital currency account holder/operator

Business Process Area(1)User X

Validator

API

API

Provider

A U
c s
c e
o r
u
n X
t

A U
c s
c e
o r
u
n Y
t

admin

A U
c s
c e
o r
u
n Z
t

Business Process Area(2)
A U
c s
c e
o r
u
n X
t

User YInterop

A U
c s
c e
o r
u
n Z
t

Interop

A U
c s
c e
o r
u
n W
t

Business Process Area(3)
A U
c s
c e
o r
u
n X
t

A U
c s
c e
o r
u
n Y
t

A U
c s
c e
o r
u
n W
t

Interop

Common Area
Business Process
Area(1)

AU
cs
ce
or

AU
cs
ce
or

Business Process uArea(2)nZ

Business Process uArea(2)nW

B
Business Process anArea(3)
k
B

t

t

)

B
a
n
k
B

(

Bank A

Business Process
Area(1))B
Business Process anArea(3)
k
A

)

)

27

(

(

B
Business Process anArea(3)
k
A

AU
cs
ce
or
u
nY
t

(

AU
cs
ce
or
Business Process uArea(2)nXtBusiness Process
Area(1)

Bank B

Validator
ProviderIssuer2. ItemWord

Definition

Item

Means of handling digital currency
In a broad sense, a digitized currency
Digital currency DCJPY in the narrow sense

Digital Currency
Common Area Coin

A deposit in the Common Area, a digital currency entity

Business Process
Area Coin

A token that poses as the Common Area Coin in the Business Process Area. Direction Token

Locked Common
Area Coin

The Common Area Coin locked in the Common Area (canonly be moved by instruction from the Business Process
Area)

Digital Currency
Account

An account in the Common Area that holds the Common
Area Coin.

Common Area
Account

A digital currency account in the Common Area that holds
unlocked the Common Area Coin

Business Process
Area Sync AccountA digital currency account in the Common Area that holds
locked the Common Area Coin for a specific Business
Process Area

Business Process
Area AccountIn the Business Process Area, an account to insert theBusiness Process Area Coin.

Business Process Area(1)User XAPI

API

Business Process
Area Account
A U
c s
c e
o r
u
n X
t

A U
c s
c e
o r
u
n Y
t

A U
c s
c e
o r
u
n Z
t

Business Process Area(2)
A U
c s
c e
o r
u
n X
t

User Y

A U
c s
c e
o r
u
n Z
t

A U
c s
c e
o r
u
n W
t

Business Process Area(3)
A U
c s
c e
o r
u
n X
t

A U
c s
c e
o r
u
n Y
t

Business Process
Area Coin

A U
c s
c e
o r
u
n W
t

Digital Currency Account /InteropInteropInterop

Common Area
Business Process
Area(1)

AU
cs
ce
or
Business Process uArea(2)nXtBusiness Process
Area(1)

AU
cs
ce
or
u
nY
t

k
A

B
a
n
k
B

B

Business Process anArea(3)

Locked Common
Area Coin

Digital Currency Account /Common Area Account

k
B

)

)

B

(

)

k
A

AU
cs
ce
or
Business Process uArea(2)nWt)(Business Process anArea(3)

B

AU
cs
ce
or
Business Process uArea(2)nZt((Business Process anArea(3)Business Process
Area(1)Business Process Area
Sync AccountCommon Area Coin

28

Bank ABank B3. Action
Word

Definition

ActionThe act of handling digital currency

Mint

Transferring part or all the User’s bank balance to the
User’s digital currency accountSynchronize

Synchronization of the balance of locked the Common Area
Coin and the Business Process Area Coin

Burn

The transfer of digital currency held by a user to that user’s
deposit balance.

Transfer

Transferring the Common Area Coin between users in
Common Area

Transfer

Transferring the Business Process Area Coin between users
in the Business Process Area.

Business Process Area(1)User XAPI

API

Transfer
A U
c s
c e
o r
u
n X
t

A U
c s
c e
o r
u
n Y
t

Validator
ProviderBusiness Process
Area Account

admin

A U
c s
c e
o r
u
n Z
t

Business Process Area(2)
A U
c s
c e
o r
u
n X
t

User Y

A U
c s
c e
o r
u
n Z
t

A U
c s
c e
o r
u
n W
t

Business Process Area(3)
A U
c s
c e
o r
u
n X
t

A U
c s
c e
o r
u
n Y
t

Business Process
Area Coin

A U
c s
c e
o r
u
n W
t

Digital Currency Account /InteropInterop
Synchronize

AU
cs
ce
or
Business Process uArea(2)
nX
t

AU
cs
ce
or
Business Process uArea(2)nWt
B
Business Process anArea(3)k
B)

Transfer

B
a
n
k
B

(

AU
cs
ce
or
Business Process uArea(2)nZt)B
Business Process anArea(3)k
A

Locked Common
Area Coin
Validator
ProviderDigital Currency Account /Common Area AccountIssuerCommon Area Coinburn

Bank A

29

Business Process
Area(1)

AU
cs
ce
or
u
nY
t

)

)

mint

Common Area

Business Process
Area(1)((B
Business Process anArea(3)k
A

Business Process Area
Sync AccountSynchronize(

Business Process
Area(1)

InteropBank B