Company: CNCKW
Filing Date: 2025-11-18
Form Type: 424B3
Source: 0001913847-25-000033
Chunk: 1

Company: Coincheck Group N.V.
Filing Date: 2025-11-18
Form: 424B3
Chunk 1
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 "Prospectus Summary — Implications of Being a Controlled Company.”

This prospectus supplement should be read in conjunction with the Prospectus, including any amendments or supplements thereto, which is to be delivered with this prospectus supplement. This prospectus supplement is qualified by reference to the Prospectus, including any amendments or supplements thereto, except to the extent that the information in this prospectus supplement updates and supersedes the information contained therein.

Investing in our securities involves a high degree of risk. See “Risk Factors” beginning on page 11 of the prospectus for a discussion of information that should be considered in connection with an investment in our securities.

Neither the U.S. Securities and Exchange Commission, or SEC, nor any other regulatory body has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

<div align='center'>PROSPECTUS SUPPLEMENT NO. 1, DATED NOVEMBER 17, 2025</div>

#### COINCHECK GROUP N.V. and its subsidiaries.
Acronyms and defined terms used in the text include the following:

| Term                           |     | Description                                                                                                                                                                                                                                                                                                                                                         |
| altcoin                        |     | A term sometimes used to refer to a cryptocurrency other than Bitcoin.                                                                                                                                                                                                                                                                                              |
| Bitcoin (“BTC”)                |     | The first system of global, decentralized, scarce, digital money as initially introduced in a white paper titled “Bitcoin: A Peer-to-Peer Electronic Cash System” by Satoshi Nakamoto.                                                                                                                                                                              |
| blockchain                     |     | A cryptographically secure digital ledger that maintains a record of all transactions that occur on a network and follows a consensus protocol for confirming new blocks to be added.                                                                                                                                                                               |
| Board or Board of Directors    |     | The board of directors of Coincheck Group N.V.                                                                                                                                                                                                                                                                                                                      |
| Business Combination           |     | The Business Combination consummated on December 10, 2024 pursuant to the Business Combination Agreement, including related transactions therein described.                                                                                                                                                                                                         |
| Business Combination Agreement |     | The Business Combination Agreement, dated as of March 22, 2022, as amended, by and among Thunder Bridge, Coincheck Parent, M1 GK, Coincheck Merger Sub, Inc., and Coincheck, and the agreements contemplated therein for related transactions to be signed or completed at closing.                                                                                 |
| Coincheck                      |     | Coincheck, Inc., a Japanese joint stock company (