KissXSis

Keita Suminoe has a problem with his twin step-sisters, Ako and Riko, being overly romantic towards him. However, he wants to attend the same high school as them, so is uncertain on what to do when he has to attend a parent teacher session involving him turning down a recommendation. When Ako and Riko find his notice letter whilst looking in his room, they go over to his school, only to be chased by several of their old admirers. Keita stops everyone and tells his sisters off for bothering him, but when he realizes why they came, he catches up with them and apologizes.

Ako decides to help Keita study in order to improve his passing rate, though both have a little trouble staying focused on the matter at hand. Ako shows Keita her chest in order to encourage him to study, but this ends up being all Keita can think about in class. Ako decides to try an alternative method, writing the notes on her body. Despite embarrassing himself in school whilst distracted, he fares better on the tests. However, when Keita likens a kiss from Ako as a penalty game, Ako gets mad and corners him, eventually making him do a wrong answer so he would have to take the penalty game. They hint at going further, but are stopped by Riko, who had been learning how to prepare food for Keita, though it ends up tasting bad. Despite this, Keita manages to improve his grade.

Keita gets annoyed with being kissed by Ako and Riko him all the time and instigates a ban on kissing. Overhearing that Keita likes sweet things, Riko tries to make him some chocolate, but can only manage something horrific. After finding one of her father's dirty DVDs, she gives Keita some chocolate lipstick, persuading him to eat it off her lips. Before they manage to go any further, they are interrupted by Ako who destroys the lipstick. Riko gives Keita another chocolate lipstick, however it was made from the horrible tasting chocolate that she had made.