[Vallen Chaos Valiant]

Spoiler for the "ending":

One wonders if the entire ending scene was canon or not.

It is either all a hypothetical "what if", or it actually happened but that after the Hitagi infatuation Monkey forgot all about her own past crush. Monkey herself said that she doesn't remember much before she met Hitagi.

I prefer to believe that it did happen. That the ghost was her first lesbian girlfriend. And that they met again in unusual circumstances. And to those who say they are from different schools; note that they are wearing different uniforms.