She entered the household under a false name, so the uncle never knew her real name.

But oddly, Sook-Hee still used her same name when they had to show their passports. That was a bit careless, no?

The dirty old man, Uncle Kouzuki, had mentioned that he had arranged things so that two women who are together would not be able to leave. So, I suppose that is why one had dressed up like a man.