Kuragi Machi ;
When Machi first made an appearance, she was already featured as a girl with problems from the past. Eventually, we found out that she comes from a pretty broken family. She has a detached half-sibling (Manabe Kakeru) studying in the same school as her. Even after all the troubles she had created due to her mental stability, she is a member of the student council, taking up the role of a treasurer.
Machi's mother still hold a grudge towards Kakeru's family and pushes Machi to perfection, not wanting her to lose to Kakeru. This is the main reason why Machi hates 'perfect' things like snow, tidy room and white chalk and always try to mess them up so that it won't look perfect anymore.
Again, more info to be added after I borrow Fel's books