The best time to leave Mitani was back when she kissed Kei, the 2nd best time is now.
Like, seriously. Back when they were in Middle School Kei had her way with Mitani's hoe ass even though they weren't dating. Now Mitani has the gall to say "a little bit too quick for that" to our confused boy Yo? They're playing chess against each other and their pawn is Yo's feelings.
God i'm too invested in this. I don't see any real way of gracefully redeeming any of these characters.