あらすじ
One day, Tougetsu Umidori suddenly receives a mysterious request from Nara Yoshino, a classmate she's rather close with. Little does she know, however, that this is only the beginning of a series of bizarre events. Soon after, an enigmatic girl in a cat hoodie shows up at Umidori's house, calling herself "BS." Thanks to her, all manner of strange things happen, including toilet borrowing, betrayal, threats, a grapple for freedom, and finally a desperate plea for mercy.
あらすじはAniListより（英語）。
