Tomohiko “Chomu” Suzuki, an overweight, friendless otaku, falls for the beautiful and popular Ayase after she casually returns a dropped keychain to him. Encouraged by this brief kindness, he changes his hairstyle, which unexpectedly catches Ayase’s attention — she nicknames him “Chomu” and begins spending time with him daily, eventually inviting him to her apartment. There, Ayase takes the lead in a one-sided sexual encounter, mocking his inexperience while simultaneously aroused by his unexpectedly large penis, treating him as a living sex toy.