the reason she doesn't remember kotoyuki being bit by the fox in childhood is because it was shu. it wasn't a literal fox bite. it was when he fell in love with her as she licked his wounds. he was abused by the adults for being the affair child of a noble family. the fox bite is the boy being beaten by their own family for not obeying their commands. hinako comforts him.

why does kotoyuki have white hair? white hair at a young age is indicitive of poliosis. a loss of pigment. it can stem from a side effect from medications taken. the white of the white claudia.