Nitori's sister Maho wants to be a model so she can meet her idol, Maiko-chan, but finds her brother draws more attention than she does. She also has a crush on a boy named Seya who has a crush on her brother, whom Seya mistakenly believes is one of her girlfriends. Pragmatic once she gets over her initial emotional reactions, Maho settles on a surprising pair of solutions: drag her cute brother along to her audition and set him up on a "friend"-chaperoned date with her crush.
Meanwhile, the bullying at school ratchets up after Nitori and Takatsuki's exchange diary is grabbed by another student and read out loud. The resulting uproar causes a rift between friends and makes both Nitori and Takatsuki question whether they should just give up trying to be themselves.
Maho's a little crazy, but she means well and I'm starting to like her. She makes things complicated (as if they weren't complicated enough already), but it's not malicious and she's aware of her own faults and willing to jump up and defend her brother from anybody who doesn't respect him, just as he proves he's willing to do for her (aw, sibling bonding!).
Even as their lives get messier, Nitori and Takatsuki find new and old allies rallying to their side and picking up their spirits.