Masahiro Setagawa is a hopeless teenager who is often used by the neighborhood bullies as an errand boy. Defenseless, Masahiro knows that nobody will ever save him. However, his life drastically changes when he meets Kousuke Ooshiba, a man known as the "Bear Killer," who takes down neighborhood gangs. A year later, Masahiro and his former friend, Kensuke Ooshiba, attend high school, only to find that Kousuke is their math teacher. While the three grow closer, Masahiro starts to view Kousuke as his "hero," and Kousuke develops an urging desire to protect Masahiro. However, their normal lives take a turn when Kensuke's childhood friend, Asaya Hasekura, returns, seeing Kensuke as more than just a friend, much to his surprise. Will the three boys be able to live a regular high school life? Or will forbidden love keep them apart forever?

If you could turn all your memories into a song, what would it resemble? Between being an exceptional student and taking care of the house alone during her mother's absence, Asuna Watase's only distraction is listening to her old crystal radio in her secret mountain hideout. One day, she accidentally tunes to a mysterious and melancholic melody, different from anything she has ever heard before. Soon after, an enigmatic boy named Shun saves her from a dangerous creature, unknowingly dragging Asuna on a long journey to a long lost land bound to surpass her very imagination, turning her once melodic life into an intricate requiem.