Nekomonogatari (Kuro) 1x3

Koyomi breaks into Tsubasa's house and is shocked to discover that she does not have her own room there. He rushes back home, where he learns from Tsukihi that people all over the city are being attacked by a mysterious cat-girl (化け猫 bakeneko?), who he realizes must be Tsubasa. When classes resume and Tsubasa never comes to school, Koyomi seeks out Oshino, who informs him that after challenging the Cursed Cat twenty times he was unable to defeat it even once. Although a Cursed Cat is usually a weak type of Oddity, this one has made use of Tsubasa's outstanding intelligence to outsmart him. He also warns that the cat must be stopped before its conscience merges fully with hers or rescuing Tsubasa will be impossible. The following day, Koyomi meets the cat, who asks him to stay out of its way, claiming that it will eventually return Tsubasa's body to her once it manages to relieve her of all her stress.