Hino Akiharu lost his parents when he was small and was adopted into his uncle's family. He didn't want to be a burden on his uncle's family and decides to enter a free boarding school as a butler, Hakureiryou high school. However, his delinquent boy-like appearance frightens the girls, who make up the majority of the students. Unable to get along with the classmates, Akiharu meets his childhood crush Saikyou Tomomi.

Kaoru Touno's family is falling apart. After the death of a sibling and his parents' divorce, he no longer feels any peace at home. Following a heated confrontation with his father, Kaoru runs out of his house and finds himself before a mysterious tunnel, which pulls him in. Bewildered by what he sees inside, he rushes to the exit, picking up a bird that looks identical to his deceased pet on his way out. Upon emerging outside, Kaoru realizes that, despite him spending just a few minutes inside the tunnel, an entire week has passed. The bizarre experience leads him to remember the rumors of Urashima Tunnel—a passage that grants wishes in exchange for one's lifespan. Given the resurrection of his pet bird, Kaoru cannot help but wonder if another visit can help fix his messed up life. However, when he returns to the entrance of the mysterious tunnel, Kaoru realizes that he has been followed by Anzu Hanashiro, a new transfer student in his class. She also knows about the rumors and asks him to help her with an experiment—it turns out that she, too, has a wish that only the tunnel can grant.

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.

It was just a usual morning. Akira Shiroyanagi, a high schooler who loves games and Konpeito (Japanese sweets), has suddenly been dragged into a battlefield by a mysterious girl who calls herself Mion. The participants are told that they are erased from the family register, involved in an experiment, and gained certain powers. Akira is determined to win the game with his newfound powers and destroy the organization. Armed with a power no one expects and his brain skills, the new period of intelligence battle begins! (Source: MU, edited)