The story takes place after the graduation of Koyomi Araragi, Hitagi Senjougahara, and Tsubasa Hanekawa. Suruga Kanbaru, the former basketball star and self-described admirer of Senjougahara, finds herself alone as a third-year student at Naoetsu High School. She still carries the Monkey’s Paw on her left arm, a supernatural remnant that once transformed her into the Rainy Devil. To prevent it from awakening again, she binds her arm to her bed each night, living in constant, quiet dread. The only person she knows who still understands aberrations is the underclassman Ogi Oshino, a mysterious figure claiming to be the niece or nephew of the eccentric folklorist Meme Oshino.

Kanbaru hears a troubling rumor spreading through the school about a Devil who can grant any wish. Fearing that the rumor refers to her own cursed arm, she investigates and discovers that the so-called devil is actually an old rival from her middle school basketball days: Rouka Numachi. Once a formidable opponent Kanbaru never had the chance to face in an official match, Rouka now walks with a limp from a career-ending leg injury. She claims to be collecting misfortune. As a ghost who has not realized she is dead, Rouka acts as a counselor, listening to people’s problems and absorbing fragments of their unhappiness, which manifest as parts of a demon she is assembling piece by piece.

The central conflict arises when Kanbaru awakens one morning to find that her Monkey’s Paw has vanished. The narrative follows her attempt to recover her arm while confronting Rouka’s hollow philosophy. Rouka believes that collecting misery from others gives her existence meaning, yet she is ultimately a tragic figure who committed suicide after her basketball dreams were shattered. Kanbaru must accept that the arm she considered a curse was also a part of her. The climax culminates in a one-on-one basketball game between the two former rivals, a match that Rouka always wanted but never got in life. By finally facing her opponent on the court, Rouka resolves her lingering regrets and ascends, while Kanbaru reclaims her arm and decides to live with her burdens rather than simply fear them.