Kirie Goshima's daily life in Kurouzu-cho is disrupted by strange occurrences related to spirals, which she initially overlooks. Her boyfriend Shuuichi Saito's father is particularly fixated on a snail shell, and Shuuichi mentions his father's unusual behavior. It turns out the town's infatuation with spirals is more than just a quirk, and eventually leads to a series of disturbing events that drive the residents of Kurouzu-cho to the brink of madness.