Not quite what I expected based on the start. The uncle isn't the scumbag I thought he was based on his early actions and the genre tropes, and despite its darker moments (several near rapes and one successful one), the ending is quite vanilla in tone.
So the parent already ready for the uncle (dad's younger brother) and their daughter get together when they let her stay with him. So in case they get together as Japan modern law do not allows uncle&niece marriage they can go to France or other countries that allows uncle&niece marriage. So they went to France to live.
The one get the bad deal here is the female coworker of the uncle, she thought she get a decent man, turn out he was a trash dude. lol