Really random theory here and I doubt it'll go this way, but hear me out. I think the twist in this whole thing might end up being that Mitsu has a crush, not one Megumi but on Genta. Toki originally says that Mitsu talks like he's stressed around his friends, but later is confused when Mitsu is talking to Megumi alone and Toki no longer hears anything wrong in his voice. Another clue to this might be when Toki mentions becoming Mitsu's friend and says it might be best to become a male. Mitsu looks concerned for a second and suggests Toki looks more like a girl.
Again, I kind of doubt the story will go that way, but wanted to share my thoughts just in case.