Board Thread:General Discussion/@comment-29619328-20160813152202/@comment-25593389-20170108161328

Salubri : The information about Isshin was that he was the head of the whole family while coming from a branch of the family. Which means that he was born from the branch family but became the head of the whole clan for some reason :

- Power exceeding those of the descendants of the main family.

- No descendants in the main family.

so

If it is the second case and the main family indeed lost his standing and the branch families progressively took the head of the family. It could explain why the clan was banished from the 4 great noble families, due to the death of last promising descendant of the branch family (kaien) and the fact of the whole clan being now leaded by the branch family.

It could have been enough to kick them out of the 4 great noble families.