http://www.edo-tokyo-museum.or.jp/english/

Pay close attention to the Canadian Representative's Signature, he signed on the wrong line causing a chain effect of signatories signing on the wrong lines.

According to the Ministry of Foreign Affairs [MOFA] of Japan....
: The Japan-owned book of "Instrument of Surrender" is kept by the Diplomatic Record Office of the MOFA.
: A replica of the Japan-owned book is on display at an exhibition room in the annex to the Office.
: The book had some country names corrected after the ceremony, at which the representative for Canada signed in a wrong place, causing representatives of three other countries to sign in wrong lines.

- Ministry of Foreign Affairs: Qs and As on diplomatic records: postwar years of Showa - page in Japanese
http://www.mofa.go.jp/mofaj/annai/honsho/shiryo/qa/sengo_02.html#12
- Diplomatic Record Office [ gaikou shiryou-kan ] of the MOFA - page in Japanese
http://www.mofa.go.jp/mofaj/annai/honsho/shiryo/index.html
: Open: 10:00 - 17:30.
: Closed: Saturdays, Sundays, public holidays, extra closed days.
(Check on the phone before visiting that it does not fall on a closed day.)

The web site of Edo-Tokyo Museum suggests
: Items on Permanent Exhibition are changed twice a month.
: At its 5F the Museum has not only large two zones for Permanent Exhibition but also a smaller zone named "Second Special Exhibits Gallery" for exhibitions on particular theme(s), which are arranged 7 or 8 times in a year.

If the original book were considered to be an item which could be on easy-contact exhibitions, like those in Edo-Tokyo Museum, then the MOFA would not have needed to prepare its replica for visitors to the Office, I think.

(sarcasm)

I'll contact the edo-museum and ask them directly.

Anyway, I presume the purpose of the original question is to know where and how to see the Japan-owned book, regardless of whether the item is a real book or a replica.