How to find your Japanese ancestors' koseki from the United States

Many Japanese American families know a grandparent's name, a ship, perhaps a prefecture — and little else. In Japan, the most complete record of a family is the koseki, the family register kept by each city, town and village office. This guide explains what a koseki is, who may request one, and what you need before you start.

What is a koseki?

A koseki (戸籍) is Japan's official family register. It records births, marriages, adoptions, deaths, and how each person is related to the others in the household. Each register is kept by the municipal office of the family's honseki — its registered "home" address — not where the family actually lived.

When a family member emigrated, the register in Japan usually continued. That is why your great-grandfather's birth, his parents' names and his siblings can often still be found there, more than a century later.

Who may request an ancestor's koseki?

Under Japan's Family Register Act, a person may request the registers of their own lineal ancestors and descendants. In practice, this means a direct descendant — a child, grandchild or great-grandchild — can obtain the records of the ancestors in the direct line, wherever that descendant lives today.

Relatives outside the direct line (for example, a great-uncle's descendants) are a different matter. Whether their records can be obtained depends on the situation, so it is worth asking before you begin.

The key you need first: the honseki

A request goes to one specific municipal office, so you need to know — or narrow down — the ancestral honseki. Families often find clues in:

passenger lists and immigration papers that name a prefecture or village,
letters, photographs and keepsakes with Japanese writing on them,
church, temple or community records kept in the United States,
wartime and postwar records that list a place of birth.

A clue that seems small — a village name written in kanji on the back of a photograph — can be enough to start.

Why requesting from abroad is hard

Language. Requests and records are in Japanese. Older registers are often handwritten in a cursive style that is difficult even for many Japanese readers.
Place names have changed. Many villages were merged into larger towns over the past century, so the office that holds the record today may have a different name.
Proof of relationship. Each step back in time must be shown to connect to you, one generation at a time.
Payment and mail. Fees and return postage are set up for people living in Japan.
Records are not kept forever. Older registers that have been closed are kept for a limited period, and some very old records may no longer exist. Starting sooner rather than later is wise.

How we help

Kakeru Legal Office is a licensed judicial scrivener (shiho-shoshi) office in Hiroshima. With a letter of authorization from a direct descendant, we request the registers from the municipal offices in Japan, read and translate them, and turn them into a family tree in kanji and English. We prepare the letter of authorization for you in Japanese and English — you only sign it.

Before you commit to anything, we offer a free assessment: send us whatever you have, organized or not, and we will tell you whether the trail looks traceable.

Every family's records are different. What survives in Japan cannot be guaranteed, and we will tell you honestly what the records show.

Ask for a free assessment See fees