A popular high school student, Oma Higurashi, dozes off on the train home and wakes up at a station he has never seen before, a place labeled Sasaragi Station. A missing girl named Inami Mayura crashes onto the platform, and before he can process what is happening, a fierce gunfight erupts around them. Oma quickly realizes that he has stumbled into a deadly otherworld called the Batsuikai, a realm where people are driven to kill one another and where human minds can be consumed, turning them into mindless beings known as Agaribito.

Determined to escape before losing his own sanity, Oma joins forces with Mayura, who is also trying to find a way back. Their goal is to reach Sasaragi Station, the apparent exit to the real world. Along the way, they encounter other survivors: Erika, a former police officer nicknamed Blood Puddle, and Fasu-ko, who possesses a detection ability. Together they form a joint retreat front to survive the hostile environment. The path is blocked by powerful adversaries, including a feared boss called the Black Woman who rules one of the territory’s domains. The group must navigate the chaos of the Batsuikai, engage in gunfights, and unravel the mysteries of this occult-infused world in order to make it back alive.