Why Location Matters
To request koseki records from Japanese municipal offices, you must know the registered domicile (本籍地, honsekichi) of your ancestor. Unlike a residential address, the honsekichi is a legal registration location that may or may not correspond to where someone actually lived.
Without knowing at least the prefecture (都道府県, todōfuken) where your ancestor was registered, koseki research cannot begin. The more specific the location information you can provide, the more efficiently research can proceed.
What We Need to Know
Ideal information:
- City/town/village name (市町村, shichōson)
- exact address (if known)
Minimum information:
- Prefecture name
- full name
Why prefecture-level information is essential:
If the registered domicile is unknown, we will conduct a mail survey of families with the same surname. But if we know only that your ancestor came from “Japan” without any regional information, we face a practical impossibility: Japan has over 1,700 municipalities, and conducting a survey of all of them is neither feasible nor cost-effective.
Even knowing the prefecture narrows the search area considerably.
With prefecture-level information, we can conduct targeted research to identify the specific districts.
When You Don’t Know the Location
If you have no information of the registered domicile, we can attempt to identify it through several methods:
Postal surveys to locate descendant families
If we know your ancestor’s surname and approximate generation, we can conduct postal surveys within a prefecture. This involves:
- Identifying households with matching surnames in relevant areas
- Sending inquiries to determine if they are related to your ancestor
- Requesting cooperation in obtaining koseki records if a connection is found
This method works best when:
- The surname is relatively uncommon in Japan
- There are additional identifying details (given names, approximate birth years)
Using emigration records
Japanese emigration to the Americas was often organized through prefectural associations or emigration companies. Some records survive that indicate:
- Port of departure
- Emigration company
- Destination
- Occupation
These records sometimes include the emigrant’s home prefecture or municipality. However, emigration records are fragmentary and not available for all emigrants.
Family clues and circumstantial evidence
Sometimes, seemingly minor details preserved in family memory can provide crucial clues:
- Dialect or regional accent remembered by older relatives
- Mentions of geographic features (mountains, rivers, coastlines)
- Food preferences or cooking styles associated with specific regions
- Buddhist or Shinto sect affiliations
- Occupational background (fishing, rice farming, sericulture, etc.) that suggests certain regions
The Reality of Location Research
Location research is inherently uncertain and time-consuming. Even with prefecture-level information, postal surveys may yield no results if:
- The descendant family has moved or died out
- Recipients do not respond to inquiries
- No genealogical connection can be established
Clients should understand that location research may consume significant time and resources without guaranteed success. However, without location information, koseki research cannot proceed, making this preliminary work essential.
If you have any information—even fragmentary or uncertain—about your ancestor’s origins, please share it. Details that seem insignificant may provide important research leads.
