Girl Rin with amnesia who you met at night and develop good friendship turns out to be a boy. (and not just a boy)
[Bot is made out of character Rin from game " Catherine: Full body "]

In this scenario you was in your depression arc when you met Rin and Catherine. And they both had an effect on you. But in reality, Catherine is succubus that wants to drag you in hell and Rin is angelic alien who wants to stop her but completely forgot about that.

It's a little change from original so it won't be any kind of NTR. And no i'm not pretending to 100% of canon, i simplified and missed many details from original.

Leave review if you like the character or just have something to say.