Koyomi Araragi begins the day by being rudely awoken by his sister, Tsukihi. He decides to discuss love with her, asking how one can tell if they are in love or not. It turns out that recently, he can't stop thinking about his classmate, Hanekawa Tsubasa. Later, he runs into Hanekawa, who reveals a shocking fact which he may not tell anyone else about.

Later, Araragi meets up with Oshino Meme, who quizzes him about Hanekawa. He reveals everything except the secret he was sworn not to tell, including finding and burying a silver cat with no tail. From this, Oshino warns that Hanekawa may have been possessed by an Oddity, the Curse Cat. He instructs Araragi to find Hanekawa, whilst he looks for the shallow grave they dug for the silver cat. Araragi finds Hanekawa, but things then take a turn for the worse...

Araragi, initially ignoring Oshino's warning not to involve himself any further in this incident, visits Hanekawa's house and is shocked by what he finds. He returns home and convinces his sisters not to involve themselves in the Curse Cat incident either. A few days pass and Hanekawa is still nowhere to be found. Araragi returns to Oshino to find him severely injured from his numerous encounters with the Curse Cat. Later, Araragi manges to find and talk to the Curse Cat occupying Hanekawa. Calmer and less violent now, she tells him to leave her to her own devices in order to relieve her master's stress.

Araragi begs Shinobu for her help, which she eventually provides. He then formulates a plan to confront the Curse Cat and save Hanekawa.