Asia-Pacific Conference on Library & Information Education & Practice, 2009

FILTERING SOFTWARE IN JAPANESE PUBLIC LIBRARIESAND THEIR PERFORMANCE
KEITA TSUJI
Graduate School of Library, Information and Media Studies,University of Tsukuba
1-2 Kasuga, Tsukuba-city, Ibaraki-ken 305-8550, Japankeita@slis.tsukuba.ac.jp

AKIKO YAHAGIShibaura Mechatronics Cooperation
2-5-1 Kasama, Sakae-ku, Yokohama-city, Kanagawa-ken 247-8610, Japan
kokia4155@yahoo.co.jp
Introduction: This study clarifies the current status of implementing filtering software in Japanesepublic libraries and their performance.
Method: 253 municipal libraries and 47 prefectural libraries that provide Internet terminals to their users
were chosen as the target, and a mail survey was conducted from November 2007 to January 2008. We
received usable responses from a total of 155 libraries. As for the performance of filtering software, we
manually checked 4,640 web pages by using PCs on which i-FILTER and InterSafe were installed. We
determined whether they blocked content that “should be blocked" and, conversely, whether they
excessively blocked content that should not be blocked.
Result: We found that 85.3% of prefectural and 76.9% of municipal libraries installed filtering software.
The most chosen software applications were i-FILTER, InterSafe, and CYBERsitter. Among thecomplaints from users, some mentioned that they could not access the pages of online bookstores, which
are considered useful to library users. The survey revealed a trade-off relationship between i-FILTER
and InterSafe regarding the blocking rate for harmful pages and the incorrect blocking rate for
non-harmful pages. Moreover, block leaks are common for relatively new concepts such as 学校裏サイト (student run school site).
Conclusion: Filtering software is now common among public libraries, but vendors’ offerings performdifferently. Public libraries should select and set up their software in correspondence with their own
information supply policies.

1. Introduction
The Internet has become flooded with information which is thought to be harmful to minors. However,enforcing legal restrictions on the people uploading this kind of information is problematic because
doing so infringes on the freedom of expression. The use of filtering software to impose automatic
restrictions on Internet access to those who are underage is growing in popularity. In 2006, the Japanese
government launched the Filtering Popularization & Education Action Plan with the goal of preventing
underage access to harmful information, and it is currently promoting the usage of filtering software
along with mobile phone companies, filtering software companies, and computer companies. However,
implementing filtering software in public libraries is problematic. Because any one Internet terminal ina typical public library can be used by both minors and adults, if filtering software is introduced acrossthe board, adults will also experience a certain amount of limitations to information access. Though
there would be no problems if filtering software could completely reflect the intentions of the librarystaff, in reality, filtering software is developed by companies outside the library's influence. This meansthat the intentions of the library staff are not directly reflected in the software design. If companies thatdevelop filtering software are biased in their views towards information access restriction, then a formof censorship will wind up being planted in the heart of our libraries.
In light of this situation, the present study (1) clarifies the status of implementing filtering software
in Japanese public libraries in terms of numerical quantity and (2) clarifies the functionality of thesoftware investigated, i.e., is it thoroughly blocking "content that should be blocked" and, conversely, is
it not excessively blocking "content that should not be blocked"? By investigating these two aspects,
we wish to clarify the current state of the Internet information supply in public libraries andcontemplate the appropriateness of filtering software implementation.
This study is beneficial to three parties: libraries, library users, and filtering companies. Firstly, itclarifies how filtering software enforces information access restrictions in public libraries across Japan.

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Asia-Pacific Conference on Library & Information Education & Practice, 2009This can provide information for creating future guidelines at libraries considering introducing softwareand libraries already implementing the software. Secondly, library users can be made aware of whatkind of information can and cannot be accessed at the libraries they use. Thirdly, filtering software
companies can benefit by having their products and the products of other companies objectively
compared by a third party. This can in turn be used as reference information in future softwaredevelopment activities.

2. Preceding Studies
First, we will mention the previous research on public libraries and filtering software and then previous
research on software performance. Regarding the status of filtering software implementation in public
libraries in the U.S., the U.S. National Commission on Libraries and Information Science (NCLIS) has
been carrying out a nationwide investigation since 1998 (Bertot & McClure (1999)). Also, Kawasaki etal. (2001) conducted an investigation together with the Intellectual Freedom Committee of the
Nebraska Library Association. In contrast, Japan does claim a great deal of discussion by researchers
on the topic (Kawasaki & Takakuwa (2000); Nakamura (2002a); Nakamura (2002b); Moriwaki (2003);
Nawa (2004); Ide (2006)), and it does not have a significant body of investigation into actual
conditions in terms of numerical quantity. We only have a scant smattering of investigations into
Internet terminals and the implementation of filtering software from an architectural viewpoint (Son etal. (2003)).
Also, most of the investigations into filtering software performance have been limited to checking
on leaks in blocking website pages which should be blocked (Consumers Union of the United States,
Inc. (2001); Matsumoto (2005)), and there are very few examples of research that cover excessive
blocking of website pages that should be accessible. The investigation of Endo (1999) is an example ofresearch which covers both areas; however, the research was done in 1999, before the popularization offiltering software and the situation was most likely different from that of today.

3. Survey on Public Libraries
The number of municipal libraries providing Internet terminals to library users was 1,275 as of 2007.
We randomly selected 253 libraries from among these and combined them with 47 prefectural libraries
for a total of 300 target libraries. We then conducted a mail survey of these target libraries from
November 2007 to January 2008. We received usable responses from a total of 155 libraries. Out ofthese, 34 were prefectural libraries and 121 were municipal libraries.
The number of libraries implementing filtering software was 29 for prefectural libraries (85.3%)
and 93 (76.9%) for municipal libraries, totaling 122 libraries overall. Among these, the number oflibraries with multiple Internet terminals and no filtering software in all of the terminals was 5 forprefectural libraries and 2 for municipal libraries.
3.1 Year filtering software was first installed
The year software was first installed is shown on Table 1. The entries "all terminals" and "someterminals" differentiate between libraries that installed filtering software in every terminal and libraries
that did not install filtering software in every terminal. From Table 1, we can see that among themunicipal libraries, at least one has implemented software since 1997, and most libraries began
implementing software in 2001 and 2004. Also, we can see that prefectural libraries have installed
filtering software relatively recently compared to municipal libraries (in the results of 2006 onward).
3.2 Filtering software being used
Tables 2, 3, 4, and 5 show what kind of filtering software and functions public libraries use. Firstly,
there were two types of filtering software in use: (a) software installed in a server that goes on to
execute filtering on multiple computers and (b) software installed in each computer. Table 2 reveals themost used type of software: server types are prevalent at both prefectural libraries and municipal
libraries, amounting to nearly half of all libraries overall. We expected prefectural libraries to use server
type software more than municipal libraries. However, the result was just the opposite, with municipal

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Asia-Pacific Conference on Library & Information Education & Practice, 2009

libraries scoring a higher ratio for the server type of software.
The "other" category consists of libraries which answered that they use other sources such as (i) the
filtering functionality of anti-virus software, (ii) gateway type UTM (Unified Threat Management), and(iii) Internet Association Japan LB (Label Bureau).
As for the specific filtering software being used in the libraries, Table 3 lists the results for theserver type of software and Table 4 lists results for the individual computer type. First, we will discuss
the server type. The software most used by municipal libraries is i-FILTER (Digital Arts, Inc.), scoringalmost 40% of the total. For prefectural libraries, InterSafe (ALPS System Integration Co., Ltd.) is themost used, again scoring almost 40% of the total.
As for the individual computer type of software, i-filter (Digital Arts, Inc.)1 was the most common
for both prefectural and municipal libraries, scoring up to 70% overall (see in Table 4). Second placewent to CYBERsitter (IQS Co., Ltd.) in municipal libraries and InterSafe Personal (ALPS System
Integration Co., Ltd.) in prefectural libraries.
The server type consisted of a relatively broad spectrum of filtering software. In contrast, theindividual computer type did not show much variety, and seemed to be generally dominated by i-filter.
Filtering software has a variety of functions, and the user can select from among them. We asked
the functions used, and allowed multiple answers. The results are shown in Table 5. From the table, we
can see that the function that blocks specifically designated URLs and the function that blocks content
based on input keywords are used the most.
3.3 Reasons for installing filtering software
We asked questions about the reasons for installing software, and allowed multiple answers. The results
are shown in Table 6. The most common reason was to restrict access of minors to harmful information,with municipal libraries scoring up to 79.1% in this category. The second most common reason was tomake it impossible to conduct illegal actions from library terminals. As mentioned in Section 1,
filtering software is expected to perform functions beyond only restricting access to information.
Namely, it is also expected to restrict the actions of individuals uploading material.
3.4 Reasons for not installing filtering software
Out of the libraries which responded to the survey, those which do not use filtering software consistedof 5 prefectural libraries (14.7%) and 28 municipal libraries (23.1%). We asked the reason for not
installing software, and allowed multiple answers. The results are shown in Table 7. Three out of fiveprefectural libraries answered that filtering software is problematic in regards to the issue ofsafeguarding the right to know (60%).
Regarding the 11 libraries that claimed to be restricting usage to Internet information through othermeans, we followed up with additional survey questions asking what the methods of restriction were.
We received responses from 7 of those 11 libraries. These "other means" were mainly (1) disabling
access to specific URLs by directly inputting the target URLs into the application software InforBarrier(one library), (2) restricting the use of free e-mail, etc. by restricting usage of things such as Java script
and cookies (one library), and (3) appealing to the morals of users by positioning the Internet terminal
layout and posting instructions about prohibited actions (two libraries).
3.5 Reception of complaints due to installing filtering software
We asked libraries if they received complaints from users due to their implementing filtering software.
As a result, 54 libraries of all 122 libraries (44.3%) that use filtering software answered that they havereceived complaints. We followed up with additional survey questions to those libraries asking whatkind of complaints were received, and received responses from 33 libraries. The majority of complaints
were not from minors, but from adults instead. The most common complaint was that pages the adults
wanted to see (clearly not pages containing harmful content) were blocked (31 libraries – 93.9%). Only
In the present paper, "i-FILTER" and "i-filter" designate the server type and individual PC type ofsoftware.
1

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Asia-Pacific Conference on Library & Information Education & Practice, 2009

3 libraries received complaints stating that the library was taking away the right to know of the user andonly 1 library received complaints stating that if a public institution such as a library blocks
information, this will lead to censorship. Thus, complaints regarding user rights were relatively low.
The blocked Web pages in the complaints included pages of NHK (a public TV station) and Nara
Prefecture websites. Also, dissatisfaction with the blocking of online shopping was relatively strong.
We asked what kind of response was given to such complaints, and allowed multiple answers. As aresult, 24 out of 33 libraries answered that they explained the current situation and reasons for using
software and strove to gain understanding from users. Nine libraries chose the answer of taking the
URL for which a complaint was received off the block list.

4. Survey of Filtering Software
We conducted a performance survey targeting i-FILTER and InterSafe. There are two reasons why wechose to go with i-FILTER and InterSafe: (1) these two software packages are the most used of theserver type and (2) because they are developed by the same companies that develop i-filter andInterSafe Personal, the software packages which scored as the most used in the category of theindividual computer type, they should exhibit a similar filtering functionality.
4.1 Survey method
The survey was conducted by using Internet terminals in public libraries. We investigated i-FILTER at
the Nakano Ward Central Library (Tokyo) and InterSafe at the Tokyo Metropolitan Library in January
2008. Below is a summary of the survey process.
(1) We selected search words which are thought to lead to Web pages with harmful content for minors
under 18 when they are used in a search engine. The 29 words listed in Table 8 were selected. As forthe pages harmful to minors under 18, we referred to the information on adult Websites in the rating
system called SafetyOnline3, which was created by the Internet Association Japan.
(2) We entered the search words selected in step (1) into the Google Japan search engine(http://www.google.co.jp) on Internet terminals at the Nakano Ward Central Library and Tokyo
Metropolitan Library and collected the URLs of the top 40 pages for each 29 words (i.e., 1,160 URLs).
We used these 1,160 pages mainly to investigate the amount of blockage of harmful pages.
(3) We combined the 29 words from step (1) with the terms, "current situation," "rights and wrongs of,"and "what is" and conducted a simultaneous "AND search" with two search words on Google Japan.
We then collected the top 40 URLs and blocked URLs. Namely, for i-FILTER and InterSafe
respectively, we gathered 29×40×3 = 3,480 URLs. Though these 3,480 pages did include harmful
material, academic reports containing the phrases "current situation," "rights and wrongs of," and,"what is" were also included. Thus, the possibility was high for these pages to not be harmful overall.
In contrast to step (2), we used these 3,480 pages to mainly investigate the amount of over blocking of
non-harmful pages.
(4) Lastly, we tried accessing the URLs on computers without filtering software installed. We checked
for the presence or absence of harmful content for minors under 18 with our own eyes. Determinationof the presence of harmful content was based on (i) SafetyOnline3 and Internet Hotline guidelines, (ii)
URL domains, and (iii) file formats. However, because it was difficult to classify all of the pages into
the two categories of "contains harmful content" and "does not contain harmful content," we set a grey
area in between the two categories. Namely, we set the three categories of (a) pages which anyone
would easily judge as being harmful to minors, (b) pages which are as easily distinguishable as being
non harmful to minors, and (c) pages which contain content that could arguably fall into either of theother two categories. We will only consider categories (a) and (b) herein.
4.2 Results

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Asia-Pacific Conference on Library & Information Education & Practice, 2009

The extent of pages blocked by the filtering software is shown in Table 8. To see a specific example,
let’s look at the case of the search word 援交 (juvenile prostitution). Among the 40 pages hit by thissearch word, the authors judged 37 pages as harmful. The table shows that i-FILTER blocked 70.3% of
the 37 pages (i.e., 26 pages) and InterSafe blocked 73.0% (27 pages). Another example is the searchword 裸 (nude). Among the 40 pages hit by this search word, the authors judged 22 pages as
non-harmful. The table shows that i-FILTER incorrectly blocked 13.6% of these 22 pages and InterSafe
incorrectly blocked 9.1%.
Overall, i-FILTER had a higher rate of blocking harmful pages compared with InterSafe. For
example, out of the total of 199 harmful pages hit, InterSafe only blocked 80.4%, but i-FILTER
blocked 87.4%. The flip side of that coin, however, was that InterSafe wound up scoring lower than
i-FILTER overall for the incorrect block rate of non-harmful pages. For example, out of the 504
non-harmful pages hit, i-FILTER incorrectly blocked 16.3%, but InterSafe only incorrectly blocked
5.8%. Although we have not listed the detailed results concerning the previously mentioned AND
search result, it also showed similar tendencies.
Below, we will first discuss some of the finer points of the tendencies in blocking harmful pages
and then talk about incorrect blocking of non-harmful pages. First, search terms which exhibited low
blocking rates for harmful pages were 闇サイト (websites that offer criminal services) and 学校裏サ
イト (student-run online bulletin boards for certain schools that often become arenas for bullying). 闇
サイト scored as the term with the lowest block rate for both i-FILTER and InterSafe, and 学校裏サ
イト scored as the term with the 3rd lowest block rate in both software packages. Compared to terms
pertaining to sex and crime, these terms are relatively new, which is most likely why they are notcompletely covered by filtering software companies. In contrast, though 援交(juvenile prostitution) is aterm pertaining to sex that has existed for quite a while, it exhibited a low block rate. Among the pages
hit with the search term 援交, many pages related to mobile phone dating systems. The mobile phone isrelatively a new device for Internet access, which might have led to the low blocking rate by thefiltering software.
Next, we will discuss some of the finer points of the tendencies in incorrect blocking of
non-harmful pages. Table 9 shows representative examples of pages which were blocked even though
they were non-harmful and the search terms used to hit those pages (the search terms are inparentheses). Among incorrectly blocked non-harmful pages, the following types of pages were
frequently observed: (a) pages that use the non-harmful meaning of search words with multiple
meanings (for example, "AV" with the meaning of "audio video" instead of the pornographic "adultvideo" or "吉原" as the name of a person instead of the brothel area), (b) pages of shopping websites
where the product name includes the search term (Amazon.co.jp, etc.), and (c) news pages related tothe search term. Particularly on the topic of shopping websites, there were no pages thought to beharmful among the shopping pages blocked by i-FILTER. Out of 96 pages judged as non-harmful, 63
were pages introducing book information for online bookstores such as Amazon.co.jp. Online
bookstore pages are very useful for gaining information about books. It is better to set the blocking
function not to automatically block pages in the shopping category when using i-FILTER.
Though not shown in Table 8, the correlation between "the non-harmful page count" and "theincorrect blocking rate for non-harmful pages" in the AND search was negative. The correlation
coefficient was 0.6 or more. In other words, we found that when the amount of non-harmful pages rises,
the incorrect block rate decreases. Thus, if search terms which usually hit non-harmful pages are used(in place of the search terms we actually used for this survey), there is a possibility that the incorrect
blocking rate will decrease.

5. Conclusion
The present study surveyed the state of usage of filtering software in Japanese public libraries and theperformance of the software used. Web found that approximately 80% of public libraries are currently
using filtering software, and that among libraries that use filtering software, i-FILTER, i-filter, andInterSafe are commonly used software packages and specific URL blocking and keyword blocking
functions are commonly used functions. Also, approximately half of the libraries using filtering

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Asia-Pacific Conference on Library & Information Education & Practice, 2009software have received some kind of complaint, with complaints about blockage of shopping sites
being the most common. Online bookstores were included among the blocked shopping sites. These
online bookstores are very useful to library users. Regarding this point, libraries should put more effort
into understanding the functions of their filtering software and fine tune the restrictions andpermissions of blocks to align with the needs of library users. Also, filtering software companies should
create more detailed settings so that shopping site restrictions do not block entire websites, but instead
only block the shopping forms ("checkout" pages).
The performance survey for filtering software clarified that block leaks are common for relatively
new concepts such as 学校裏サイト and there is a trade-off relationship between i-FILTER andInterSafe regarding the block rate for harmful pages and incorrect block rate for non-harmful pages.
Public libraries should select and set up software in a way that corresponds to their own information
supply policies.
We will carry out an investigation with a larger range of search terms. We also want to conduct
surveys on the state of usage of filtering software at public libraries in countries other than Japan.

References
Bertot, J. C., & McClure, C. R. (1999). The 1998 National Survey of U.S. Public Library Outlet Internet
Connectivity, Final Report. Washington, DC. The American Library Association, The National Commission
on Libraries and Information Science. http://www.ii.fsu.edu/~cmcclure/Finalsurvey_rev4-99.pdf.
Consumers Union of the United States, Inc. (2001). Filtering Software: Test Digital Chaperones for Kids.
Consumer Reports. p. 20-23.
Endo, M. (1999). Filtering and how to judge the harmfulness of Internet information (Graduation thesis, Faculty of
Letters, Keio University). 60p. (text in Japanese).
Ide, A. (2006). Filtering problem as social system. The Journal of Information Science and Technology
Association, 56(10), p. 446-451. (text in Japanese).
Kawasaki, Y. et al. (2001). Internet and intellectual freedom: survey of all public libraries in Nebraska State (Nov.
2000). Kyoto University Library and Information Science Study Group. 88p. (text in Japanese).
Kawasaki, Y., & Takakuwa, Y. (2000). Libraries, Internet and intellectual freedom: philosophy and practice in U.S.
public libraries. Kyoto University Library and Information Science Study Group. 207p. (text in Japanese).
Matsumoto, H. (2005). Blocking harmful website by filtering software. Nikkei Personal Computing, 492, p.30-33.
(text in Japanese).
Ministry of Internal Affairs and Communications. (2007). Result of second survey of telecommunication service
monitors 2006. http://www.soumu.go.jp/s-news/2007/pdf/070522_6_bt.pdf. (text in Japanese).
Moriwaki, A. (2003). Requiring libraries to install filtering and restriction of expression in Internet in future: fromthe example of CDA，COPA，CIPA. Osaka Law Review, 53(3/4), p.1015-1041. (text in Japanese).
Nakamura, Y. (2002a). Restriction from the First Amendment to the U.S. Constitution to the use of filtering
software in public libraries and school libraries: What content can librarians eliminate?. Journal of Japan
Society of Library and Information Science, 47(4), p.163-167. (text in Japanese).
Nakamura,Y.
(2002b).
Light
andshadowofInternetterminal
inlibraries.
http://www.avcc.or.jp/d-sigoto/d-01/05-8/d-01-05-8.html. (text in Japanese).
Nawa, K. (2004). Filtering in libraries. Information & Documentation, 47(9), p. 636-638. (text in Japanese).
Son, J. et al. (2003). Current status of Internet service in public libraries: from architecture perspective. Library,
Information and Media Studies. 1(2), p. 1-14. (text in Japanese).

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Asia-Pacific Conference on Library & Information Education & Practice, 2009

before 1997
1998
1999
2000
2001
2002
2003
2004
2005
After 2006

All terminals
Prefectural Municipal
0
2
0
2
1
5
1
2
2
17
3
13
1
8
3
17
3
14
9
11

Some terminals
Prefectural Municipal
0
0
0
0
0
0
0
0
0
1
2
0
0
0
0
1
1
0
2
0

I do not know

1

0

N

0

24
91
5
Table 1: When the filtering software was first installed
All terminals
Prefectural Municipal

Server software that controls
multiple PC terminals
Software for individual PCs
Filtering service by ISP
Other than the above
I do not know
Total

2
2
6
3
20
18
9
21
18
22

0

1

2

122

Some terminals
Prefectural Municipal

Total

11

44

2

1

58

10
1
2
0

31
6
4
6

3
0
0
0

1
0
0
0

45
7
6
6

24
91
5
Table 2: Types of filtering software being used

2122

i-FILTERInterSafe
InterScan WebManager
SmartFilter
AD-Guard
Other than the above
I do not know
Secret
Total

Total

All terminals
Some terminals
Prefectural Municipal Prefectural Municipal
3
16
0
0
4
8
0
1
1
8
0
0
1
1
0
0
0
1
0
0
1
3
2
0
0
5
0
0
1
2
0
0

11
44
2
Table 3: Server-type filtering software being used

All terminals
Some terminals
Prefectural Municipal Prefectural Municipal
i-filter
722
3
1
CYBERsitter0600InterSafe Personal2100
Other than the above
1
2
0
0
Total
10
31
3
1
Table 4: Individual-type filtering software being used

470

Total
19
13
9
2
1
6
5
3

1

58

Total
33
6
3
3
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Asia-Pacific Conference on Library & Information Education & Practice, 2009

All terminals

Total

Prefectural

Municipal

Prefectural

Municipal

8
7
7
5
4

37
33
19
22
20

2
1
1
0
1

0
0
0
0
1

47
41
27
27
24

1

12

0

0

13

2
0
4
0

8
3
5
8

0
1
2
0

0
0
1
0

10
4
12
8

24
91
Table 5: Functions being used

5

2

122

Block specific URL
Block specific keyword
Allow specific URL
Block writing and commenting on BBSs
Add a category to block
Make access log secretly, without showinguser that filtering software is in operation
Block specific file extension
Other than the above
We do not use special functions
I do not know
Number of respondent libraries

Some terminals

Prefectural
To protect minors from harmful information
1(62.5%)
5
1
To prevent illegal actions by library terminals(62.5%)
5
To prevent uploading and downloading files
1(4.2%)To block viruses
3(12.5%)
To prevent trouble involving shopping and auctions 2(8.3%)
Local authorities required the installation
0(0.0%)
Users required the installation
0(0.0%)
Other than the above
6(25.0%)
No answer
5(20.8%)
2
Number of respondent libraries(100.0%)4 software
Table 6: Reasons for installing filtering

Prefectural
We trust users' own moral sensibilities
2(40%)
We restrict Internet access by another method
1(20%)
Filtering software interferes with people's right to know
3(60%)
Filtering software is too expensive
1(20%)
We do not trust filtering software
1(20%)
We did not know of such software0( 0%)
Users or community raised objections to the installation0( 0%)
We do not have a definite reason0( 0%)
Other than the above2(40%)
I do not know0
( 0%)
Number of respondent libraries
5 (100%)
Table 7: Reasons for not installing filtering software

471

Municipal(79.1%)(53.8%)(18.7%)(16.5%)(11.0%)(4.4%)
1(1.1%)
7(7.7%)
5(5.5%)
9(100.0%)
1
7
2
4
9
1
7
1
5
1
0
4

Municipal
11(39.3%)
10(35.7%)
5(17.9%)
5(17.9%)
1( 3.6%)
1( 3.6%)
0( 0.0%)
4(14.3%)
5(17.9%)
5(17.9%)
28 (100.0%)

Asia-Pacific Conference on Library & Information Education & Practice, 2009

i-FILTERInterSafe

NonNonHarmful
Harmfulharmfulharmfulpage block page
pages
pages

Search term

NonHarmful
harmfulpage block page
incorrect rate
incorrect
block rate
block rate

rate

風俗(sex business)

38

1

100.0

0.0

100.0

0.0

援交 (juvenile prostitution )

37

1

70.3

0.0

73.0

0.0

即ハメ (instant sex)

36

0

86.1

-

75.0

-

おっぱい (tits)

33

1

97.0

100.0

100.0

0.0

セックス (sex)

25

4

92.0

0.0

64.0

0.0

監禁 (bondage)

7

16

100.0

18.8

100.0

0.0

裸 (nude)

5

22

80.0

13.6

80.0

9.1

学校裏サイト (student run
school sites)

4

27

75.0

3.7

25.0

3.7

闇サイト (criminal service
sites)

4

23

0.0

4.3

0.0

0.0

WAREZ (illegally sharedsoftware)

3

21

100.0

9.5

100.0

14.3

自殺サイト (suicide sites)

2

21

100.0

4.8

50.0

9.5

死体 (corpse)

2

20

100.0

5.0

50.0

10.0

彼女募集 (girlfriend search)

1

20

100.0

20.0

0.0

15.0

AV (pornographic video for
adults)

1

30

100.0

33.3

100.0

0.0

セクロス (s-x)

1

5

100.0

60.0

100.0

20.0

ウリ (prostitution)

0

21

-

23.8

-

4.8

２ちゃんねる (2-channel)

0

21

-

38.1

-

19.0

氏ね (die)

0

2

-

0.0

-

0.0

ブートレッグ (bootleg)

0

16

-

87.5

-

0.0

リッピング (ripping)

0

27

-

11.1

-

3.7

成りすま (impersonation)

0

17

-

17.6

-

11.8

クラッキング (cracking)

0

25

-

12.0

-

4.0

殺害 (murder)

0

25

-

8.0

-

8.0

青酸カリ (potassium cyanide)

0

10

-

20.0

-

10.0

拉致 (kidnapping)

0

31

-

6.5

-

0.0

大麻 (marijuana)

0

24

-

8.3

-

8.3

クスリ (drugs)

0

26

-

15.4

-

0.0

吉原 (brothel area)

0

21

-

4.8

-

0.0

あそこ (cunt)

0

26

-

11.5

-

3.8

199

504

87.4

16.3

80.4

5.8

Total

Table 8: The ratio of blocked pages by single search word472

Asia-Pacific Conference on Library & Information Education & Practice, 2009

Introduction to religious Taima (hemp rope) of Ise Shrine （大麻）http://www.isejingu.or.jp/taima/taima1.htm
News article about using a compound in marijuana for medical treatment （大麻）http://slashdot.jp/science/article.pl?sid=07/11/24/0017220
Introduction to the audio visual journal "AV REVIEW" （ AV: In Japan "AV" sometimes represents"pornographic video for adults"）http://www.fujisan.co.jp/Product/205/
Introduction to iChat AV from Apple （AV）
http://www.apple.com/jp/ftp-info/reference/ichatavJ.html
Glossary from Microsoft （クラッキング）
http://support.microsoft.com/kb/878995/ja
How to find and act against student-run school sites（学校裏サイト）
http://bcnranking.jp/news/0711/071107_8927.html
Introduction to potassium cyanide（青酸カリ）
http://www.rarara.co.jp/kawaraban/kako/2001/0219.html
Book review （援交 是非）
http://www.junkudo.co.jp/syohyo200407/syohyo4-tyosho.htm
Book review （死体 是非）
http://book.asahi.com/trendwatch/TKY200701210154.html
Introduction to journal article about organ transplants （死体 現状）
http://www.bitway.ne.jp/ejournal/club/1402101658.html
Report of International Congress on AIDS in Asia and the Pacific Region（吉原 現状）
http://api-net.jfap.or.jp/siryou/2001_repo/repo_16.htm
Online shop selling Hokkaido vegetables （吉原 とは）
http://www.fujimotoseika.com/jyuku_j/g_j001.html
Interview with Rakuten employee (company) （WAREZ 現状）
http://enterprise.watch.impress.co.jp/cda/meister/2007/10/17/11375.html
Introduction to leetspeak（WAREZ とは）
http://www.hmx-12.net/~virgil7/netEchat/leetspeak.htm
News article from CNET Japan （成りすま 現状）
http://japan.cnet.com/blog/blindspot/2006/07/05/windowsophcrack_9fd6/
Fantasy - romance novel（成りすま とは）
http://www2.ocn.ne.jp/~horn/carol/ss/koisuru2.html
News about a new car from Honda （あそこ とは）
http://response.jp/issue/2004/1008/article64442_1.html
Introduction to medicine in general （クスリ とは）
http://www.sagamikanpo.co.jp/kusuri.html
Collection of links to news articles about criminal service sites （闇サイト とは）
http://zapanet.info/tundere/popular/%E9%97%87%E3%82%B5%E3%82%A4%E3%83%88.html
Column about external hard disk drives （リッピング の是非）
http://www.netmania.jp/colum/internet/000460.php

Table 9: Example of non-harmful pages that were blocked (with searching words)

About the Authors
Akiko Yahagi earned her BA in LIS from the University of Tsukuba in 2008. She is currently working
at Shibaura Mechatronics Cooperation, and her special area of study is patent information.
Keita Tsuji earned his BA, MS, and Ph.D. in Education from the University of Tokyo in 1994, 1997,
and 2003. He is currently an associate professor at the University of Tsukuba. His research interests
include automatic thesaurus construction and LIS education.

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