The city hall asks you that where your ancestor's registered domicile was. That means you have to inform the city hall of your ancestor's registered domicile when you file the application form to obtain family registers in general.
We can obtain your ancestor's family register if you don't identify your ancestor's these information.
So please don't hesitate to make a contact us under any situation.
You can keep in touch with us anytime via our email below.
muro@e-kui.jp