Yuko Takeuchi, a celebrated author of mystery novels, receives a letter from Ai Hashimoto’s character, Kubo, a university student and an avid reader of her work. In the letter, Kubo describes hearing strange noises coming from her current apartment. Intrigued by this, Yuko decides to delve into the mystery alongside Kubo. Together, they uncover the histories of the apartment’s previous occupants, which include tales of suicide and murder.