How do people with no family history get married in Japan?
This is for research purposes. Suppose, there's a Japanese person who was orphaned at a very young age. She had to live in another country all her life. As a grown up, she comes back to Japan. She has no memories of her dead Japanese parents and knows only her own name. As the Japanese law requires family history for a person to get married, how can the person in question get married? Five stars, if you can describe the procedure step by step.
By history, it means a document called koseki. If her koseki still remains in Japan(if her parents registered her as Japanese at her birth, it remains with certainty. And it does not get deleted unless you get a citizenship of another country), then she can get married without a problem.
By family history, you mean her koseki?
How did she get a Japanese passport to leave Japan in the first place? She would need a koseki to get a passport. How did she renew a passport to return to Japan without her koseki?
If she has another nationality, she can return as a foreigner and live as a foreigner until she finds her koseki. She can get married just like any other foreigner. I know someone in this situation except she wasn't an orphan. She just doesn't know where to get her koseki.