Atsushi Hokari, Masato Kageura, Satoshi Mizukami, Ko Murakami, and Guest are students at Mikado City First High School. As classmates in Class 3-C and active Border agents, the five of them spent their days balancing school life with their duties at Border, living a perfectly normal daily life.

Then, one day after school. A classmate suddenly tells the five of them, "Find my body." Because the request was made so casually, the five of them didn't think much of it and simply went home.

That night. After finishing an ordinary day and falling asleep, the five wake up to find themselves in a deserted school at night.

At first, they think it's a dream. But as they walk through the school, they encounter Hokari, Kageura, Mizukami, and Murakami one after another. Realizing they are all in the same place, they understand this is no dream.

Eventually, as the clock strikes midnight, something begins.

Without understanding what is happening, the five are forced to wander the night school building.

And then, it appears—the Person in Red.

No matter if they run or fight, they are killed over and over again. Yet, despite dying, the five wake up to the same morning once more.

A day exactly like yesterday. And when night falls, they are back at the school.

An abnormal night that began without explanation. While gathering information bit by bit within the repeating day, the five must face the nightly "Body Search."