It all starts from a misunderstanding! Yuzuki Makoto, an introverted otaku with a huge penis and incredible sexual prowess, started dating his childhood friend, the gyaru Mizuhana Hinare, and her best friend, Saneyama Asuhi. But one day after advancing to his third school year, Makoto is called out by a kouhai gyaru, Azamaru Sena, whom he has no previous acquaintance with, and gets beaten up by her! Sena couldn't believe that Hinare and Asuhi were dating him, and mistakenly thought the two were being blackmailed. After the misunderstanding is cleared up, Sena feels deeply remorseful. To make up for it, she accepts the penalty of healing Makoto's wounds with sex...