Tsugumi Aozora

A classmate of the girls'. One night, Tsugumi has an argument with her boyfriend, confessing that she is actually male. When this is accidentally overheard by Olivia and the girls approach her, Tsugumi admits she lied in order to break up with him faster.

[Spoiler] Tsugumi's denial sets off Hanako's "animalistic sense of danger". Later on it is heavily suggested that Tsugumi is, in fact, male. [/Spoiler]