With Sayuki and Yuika declaring themselves masochist and sadist and their intent to make Keiki their master/slave respectively, one thing becomes clear: Keiki isn’t that into this. He avoided dating girls because he felt himself to normal and boring, but now he’s having nightmares as a result of Yuika’s “punishment” last week. He doesn’t even want to go to school, but Mizuha makes him, since he’s not really ill.
Things don’t get any easier for Keiki, as he’s greeted by Yuika’s bra in his shoe locker, followed by a photo of him with his shirt open lying with Sayuki, with the implication it will be distributed if he doesn’t meet with her. When he gets there, Sayuki is dressed as a maid and handcuffed; he must fish the key out of her cleavage.
All the while, the third girl in his life (not counting his sister), Nanjou Mao, keeps watching silently from afar, her gentle blushing going completely unnoticed by Keiki. But when he tells his best mate he doesn’t believe Sayuki or Keiki are the Cinderella, that friend points out Mao’s staring, who it’s directed at, and what that entails.
Mao’s passive role thus far becomes more active by necessity when Keiki is once again summoned to the clubroom by Sayuki, but is intercepted by Yuika, who ties him up and orders him to kiss her foot or she’ll steal his first kiss on the lips. Sayuki barges in to put a stop to it, and the girls, who have known about each other’s proclivities since they met, start to bicker, with Keiki in the middle.
Enter Mao, who drags Keiki, chair, rope and all, into the hall, away from the two warring girls. He blames him for being so nice to both of them and indulging them too much, and in the process betrays that she’s been observing his interactions with them very closely (we dohear a camera click when he’s fishing out the handcuff keys…was that Mao?).
When Keiki asks why this concerns her at all, Mao has no choice but to be more direct: she just plain doesn’t like it when he’s with other girls. That could well be because she’s developed feelings for her childhood friend, but it also means a third girl has decided to try and assert control over him. Perhaps not as a formal master or slave, but it’s definitely possessive and unbidden by Keiki.
Considering how uncomfortable the other two girls’ antics have made Keiki, perhaps Mao is the “Goldilocks” answer, but first he has to determine whether her particular kink (stalking?) is more or less manageable.