Is there anything redeemable about Yuka? I don't think the author necessarily intended it to come off this way but I can only assume that Yuka got with his brother to make him jealous. All this talk of injuring him and responsibility which in itself is an absolute riot to assume she could legitimately take that to the point of breaking up with him and fucking the dude in front of him instead of just telling him she wanted to be more intimate. Literally her goal was to make him make a move. Sure he was a coward, but a lot of kids are at that age. Jesus christ, she just wanted some dick. If it was Kyouhei's all the better, but she wouldn't remain in a relationship with the guy after our man left if she wasn't getting something from it.