Guide to Japanese Ancestry Research

This guide is a starting point for researching your Japanese ancestors. In this guide, “ancestry research” means finding out who your ancestors were and how they were related. Results are usually recorded as a keizu (系図), a record, written or digital, that shows the principal family relationships as a diagram, or a keifu (系譜), a record, oral or written, that states the relationships in words only.

The pages below are arranged in the order most research follows. If you are new to the subject, read from the top. If you already know what you need, go straight to the relevant table.

1. Where to begin

Most research on Japanese ancestors follows four steps.

Step	What to do	Read
1	Find the registered domicile (honsekichi) of your ancestor	Identifying Your Ancestor’s Location in Japan
2	Request the family registers (koseki) from the municipal office	Understanding Japanese Family Registers (Koseki)
3	Go back further with documents that predate the modern register system	Research Beyond Family Registers
4	Check genealogy collections and digital archives	Japanese Genealogy Collections, Digital Archives

2. Practical guides: methods, tools and cautions

Page	Summary
How to Research Your Ancestors	Mindset, strategy and methods: from family registers to local histories, old documents, temples and graveyards, and how to search libraries.
Creating a Family Tree from Koseki and Joseki-bo	Confirming the registered domicile, requesting registers by counter or mail, requesting from the previous domicile, and copying relationships into a family tree.
Relationship Terms	How to read and write relationship terms in family registers and keizu: generation counts, direct and collateral lines, and entries such as “eldest son”.
Japanese Names Before the Meiji Era	Uji, kabane, myōji and tsūshō: how names were made up before the Edo period and after the Meiji period.
Common Mistakes and Misconceptions	Five misconceptions beginners fall into, such as family crests, name order and the clan name (hon-sei).
Reference Works Cannot Be Taken at Face Value	Errors in dictionaries, local histories and removed family registers, and how to separate facts from interpretation.
Tools for Ancestry Research	Recording devices, A3-capable multifunction printers, storage, and spreadsheet, OCR and other software, rated by necessity.
Software for Creating a Family Tree	Why a spreadsheet is enough, how to lay one out, and free cloud services.
DNA Haplogroup Resources	Reference links for looking up DNA haplogroups.
Useful Links for Ancestry Research	Tools for reading old handwriting, era-name conversion, surname distribution, digital archives and legal databases.

3. Family registers (koseki) and the rules around them

Page	Summary
Understanding Japanese Family Registers (Koseki)	What the koseki is, how this household-based register records relationships, births, deaths, marriages and adoptions, and how far back it can take you.
Identifying Your Ancestor’s Location in Japan	Why you must know at least the prefecture of the registered domicile before requesting koseki, and how it differs from a residential address.
Japanese Inheritance & Koseki	Why inheritance cases need every consecutive koseki from birth to death, not only the current one.
The Illegality of Proxy Requests for Family Registers	Why requesting family registers by proxy for paid family-tree creation or ancestry research is not permitted.
Why We Cannot Predict Investigation Timelines in Advance	How the time needed depends on whether the registered domicile is already known.
Japan’s personal information database situation	Why finding a living person in Japan is difficult.

4. Names and the Japanese language

Page	Summary
Understanding Japanese Names	The structure of modern names (family name and given name) and how the order differs from Western usage.
Japanese Naming Customs	The basic principles of modern Japanese name structure.
Personal Names in Japan	How samurai names were made up in the pre-Edo and Edo periods, including the clan name (hon-sei).
Japanese Family Names and Place Names	Reading the meaning behind the kanji of family names and place names.
Linguistic Issue in Asia and Japanese	Why the language barrier makes Japanese ancestry research challenging.

5. Going back further

Page	Summary
Research Beyond Family Registers	How to extend the line into the Edo period (1603-1868) and earlier with old documents.
Japanese Genealogy Collections	A list of major compilations that bring together the genealogies of many families, the first place to look for the pre-modern period.
Genealogies	Individual entries for each compilation.
Digital Archives	A list of digital archives across Japan, from national portals to local institutions.
Temples lists and Temples	Temples by prefecture, for finding the family temple and its records.

6. For professional genealogists and probate cases

Page	Summary
For professional genealogists and Someone looking for a person	Research tasks we undertake in Japan for overseas genealogists.
What exactly do you need from Japanese genealogists?	A question to overseas probate genealogists about what they actually need.
Modern Japanese Inheritance Law	Essential knowledge for international estate professionals.
The Role of Notaries in Japanese Inheritance	How notaries fit into inheritance procedures in Japan.

7. Services

Page	Summary
Service and Fees	Ancestry research and compilation of a family biographical dictionary, with a staged payment system.
Creating JP style Family Tree & Crest service	A Japanese-style family tree and crest for display or commemoration.

8. Research and links

Page	Summary
Academic Research	The theoretical development of genealogical science.
Research papers	Papers published by our institute.
Genealogical Science Portal	A guide to institutions and systems useful for Japanese ancestry research (separate site).
Encyclopedia of Genealogical Science	A glossary of terms in genealogical science (separate site).
Links	Portal sites and societies related to genealogy.