If you live in Japan, the easiest way is to go down to your own local office and ask. Then just look it up in a book and will give you the address and contact information. Most will gladly help you, as this is a common problem for both Japanese and non-Japanese alike. Actually, it doesn't even have to be your own office. If you know the contact information for one local office in Japan, it is likely they will even do this for you over the phone. If you do not speak Japanese well, you may want to start with the foreigner's help section there where they speak English.

If your Japanese skills are good, you can also try looking things up on the internet. Search in Japanese on the -shi, -kuor other designation and perhaps "yakusho".You can check our list of Japan prefecture by prefecture contact information. It is still under construction, but links to another site that might have what you are looking for.

If you are overseas, you may want to start by callinga Japanese consulate or embassy. There should be no reason for them not to help you with a simple request to find the contact information for a particular local government office. Here is a list of Links to Japanese Consulate Generals Offices in the US on the WWW You could pretend that you have some other reason like wanting to locate a Japanese relative. You could also try to requestaddress information from your country's Consulate in Japan. In this case, if you tell them why, they should be even more likely to help you. You can call and ask the US Embassy in Tokyo for information on the consulates, or just look them up on the Internet. There is also a general site for the US Embassy in Japan. The next option may be to try calling ANY government office in Japan from overseas. If your Japanese is good, you may want to try this first. If your Japanese is not, then call anyways and try speaking English very slowly. They will likely transfer you to someone who does speak some English and will help you. If not, try to get to the foreigner's help section, where helping people like you is their job. (Well it is if you live in their jurisdiction.) A final option may be towrite toJapan's National Diet Library and ask for the address of a village office to write to. Contact information can be found on the National Diet Library English WWW page

[ADD CONTACT INFO FOR A FEW OFFICES, PERHAPS BIG ONES IN TOKYO.]

The following information is from: www.geocities.com/SiliconValley/Garage/4464/KosekiAddress1.html

Consult the below (an encyclopedia of geographical names, each volume is devoted to one prefecture and further divided into introduction, geographical names, gazetteers and sources). It contains which government office to write to for koseki information and their addresses. This text is in Japanese.
Title: Kadokawa Nihon chimei daijiten
Publisher: Tokyo : Kadokawa Shoten, 1978-1991
Subject: Japan -- Gazetteers
Author: Takeuchi, Rizo, 1907-
Other Title: Nihon chimei daijiten

Places on the WWW that look like they have copies are:
Duke University, East Asian Collection
University of Washington, East Asia Library

Other East Asian Libraries and collections may also have these invaluable references. These are most often found on larger college and university campuses. A list of East Asian libraries can be found:
East Asian Libraries on WWW Indiana University Bloomington