During his teenage years, Natsuo Fujii had to confront the heart-wrenching experience of unrequited love. He had fallen desperately for his lively and cheerful teacher, Hina, but he knew deep down that it was an impossible emotion. Trying to move on, Natsuo attended a mixer with his friends, where he met Rui, an apathetic girl. After a few drinks, they ended up at Rui’s place, where she suggested they have sex to prove that she was not naive. Despite his persistent thoughts of Hina, Natsuo agreed to Rui’s proposition.