Further thoughts:
Tachibana is a tiny little thing, but it's amazing how threatening someone can be when you give them the _Terminator_ treatment of being slow but unhinderable.
An excellent choice, especially given that she gets rehabilitated (in the audience's eyes) later.
Many of the characters have back stories that would make them at home in the Monogatari series, or even worse. These kids are carrying a lot of trauma, and some of it can't ever really be solved. Only accepted.