I'm glad people are commenting on what happened to Aoi at his last school. Their teacher from the first installment noted that his father is supposed to be strict, so Aoi probably has absolutely no outlet for what has happened to him. As
@COVERTmangamaniac noted, no wonder he is so reserved whenever other students show interest in him!
I really love the dynamic between Aoi and Hachi, where Hachi is the only person whose interested in him without ulterior motives or desire for clout. I can't wait to see where the series goes from here!
Edit: I also like how the writer incorporates different real life animals behaviors. Hachi does the flehmen response in reaction to Aoi petting his tail in the original oneshot, and here Hachi likes being inside the locker because it makes him feel safe (no doubt a joke about cats' love of boxes).
Jebed