Yeah it's the one that ran the classroom in the flashback and slapped him while trying to make him wrongly confess. The neighbor with the motorcycle celestial peaches is the learner one.
Well that hurt. I lived through most of this story just without the childhood friend's help. Even after 20 years the guitar case still smells like her. Ok. I think it's time to read some isekai trash or something. Ok.
The reason why they're trying to fix him is because he's been broken for most of his life. Bad dad, neglectful mom, sis tried to kill him, some school bullying, one girl he tied himself to went stupid and tried to make him jealous, the next woman was getting teased and didn't like that her love...
I don't think it's FMC from the future. I mean I can see it since her sanity is ready to snap. When she hops back her mind goes to her old body. At this point she's probably been resetting time for about a year. Maybe a little less. There might be other methods of time travel though so shrug.
I don't think it's her from the future. When she pops back in time she goes back to her old body. She has done this a long time at this point. The toy on the train at juuust the right spot with dropping a coupon as a reminder to someone else while messaging an IRL streamer about juicy gossip...