We havn't learned what yumi and sensei's relationship before the resets were right? I can somwhat remember yumi implying something was going on due to her constant abstent from class, but I can't imagine Akira caring about it so much that he keeps bothering Yumi?
Reset 0 Akira from what I remember forgot everything, and is already pretty fked up, what about pre-reset Akira? How was he functioning to a point where he was able to teach a class? It was all early chapter 1 so I dont remember much but I think Makoto mentioned he was pretty normal?
Now that i think about it, do we know any backstory before reset? How Akira ended up at the seemingly random spot where he is in class with ami and reset starts?
Regarding Yumi: There are many scattered fragments about him during school pre-resets. The thing about him paying more attention to Yumi than anyone else comes directly from her mouth - so it doesn't have to be entirely true, but I'd wager it is. She says he stalked her constantly, and gave her detentions, in her words they were creepy (to what extent we do not know), there is a flashback about Yumi possibly being shirtless in his office (mind you this could be from another timeline, or even not his office).
But she does say that the worst part about the detentions was he saying that she could do more with her life constantly, so maybe they weren't that creepy. In fact, she says that at one point he tracked her down and managed to make an arcade where she hung out stop accepting her there (either so that she'd come to school or so that she would stop stealing from there).
Regarding general school life: From Makoto's initial dialogues, it seems he was a normal teacher, and hardworking enough to be admired by both her and Futaba. Also flexible enough to allow Chika to skip some classes to check on her idols. The photo that we have of all girls, that Maya puts in his folder, was taken by him (can't recall the event, but we see him taking it while they pose).
Regarding his personal life: It seems he never answered Ami's affections, felt absolutely no attraction towards Ayane, didn't pursue any of the girls in any shape or form (maybe with the exception of Yumi) and instead was pretty much Maya's boyfriend for years without ever cheating on her (although not much of a wholesome relationship there).
Definitely one of the highlights of Chapter 4 for me so far.
