And Tachibana very much is the type to swiftly get attached, especially when it seems like someone is in need of guidance. He also has a good amount of experience with that whole "what is human" thing so he can give some decent advice there. (Currently of the 3 people from his canon here, he's the only one who's physically human, thought he will fight anyone who tries to claim 2 of the others aren't as one is his current best friend (much to both of their confusion) and the other used to be human and was his mentee whom he sees as his little brother. Lots of complicated feelings about what it means to be human here. :D

Also, does Ruca want to learn about motorcycles?