Episode 26 included in the ninth DVD volume of Kaibutsu Oujo.

Thirteenth season of .

Ryoka is awakened by flurry of text messages from her mother! Panicked and rushed, Mom is clearly concerned for Ryoka's safety, but she is not too keen on letting her daughter know why. Her reasoning being that nothing could really properly describe what is happening! The world might be ending! And there might be a massive new life-form on the roof of their apartment building! (Source: Denpa)

In the town of Kurouzu-cho, Kirie Goshima lives a fairly normal life with her family. As she walks to the train station one day to meet her boyfriend, Shuuichi Saito, she sees his father staring at a snail shell in an alley. Thinking nothing of it, she mentions the incident to Shuuichi, who says that his father has been acting weird lately. Shuuichi reveals his rising desire to leave the town with Kirie, saying that the town is infected with spirals. But his father's obsession with the shape soon proves deadly, beginning a chain of horrific and unexplainable events that causes the residents of Kurouzu-cho to spiral into madness.