Shikabane Hime: Kuro

Synopsis

As Nozomi attempts to seduce Ouri, the black cat shows Ouri that she is being controlled by an ever growing balloon. Classmate Mizuki Inuhiko enters his room and smacks Nozomi in hopes of getting her back to normal, but as Nozomi escapes, Mizuki tells Ouri that Nozomi loves him. Makina hears of the incidents at school and runs there, only to encounter Nozimi, who manages to bind Makina to a balloon before running away. Makina sees an illusion of a bizarre amusement park, where she finds Toya, who believes death is "happiness". Ouri catches up with Nozomi, who is about to be consumed by her own "happiness" in a form of a Shikabane. After Makina defeats Toya, it turns out to be a little girl raised by a poor family. When Toya and her parents had gone to an amusement park one day, they poisoned her and then themselves, which led her to believe that death and happiness are the same. Hizuchi, the one who revealed this story, then knocks Makina unconscious. Ouri makes an attempt to destroy the Shikabane but fails. When Hizuchi appears, he destroys the Shikabane, killing Nozomi in the process.

(Source: Wikipedia)