Responses
It was so sick and depressing that he has to take on the identity of her brother and she’s happy to sleep with someone she regards as her brother. This is some twisted really fucked up shit that I’m not prepared for
I think it's because he is now legally recognized as Masaki so they still need to act as siblings buuuutttt it doesn't explain why she really, completely and genuinely regard him as her brother now (even when they are doing the deed). But even then, her inital perception of her biological brother is already near-incestuous imo.
But why does she have to keep calling him brother?! They moved pretty far away so it's perfectly fine for her to stop. Not into that weird sibling kink shit but it was still good.