Asuka Morisaki is a socially isolated high school student, an outcast among peers with no meaningful friendships. She navigates school life largely invisible to classmates, fostering deep loneliness. This existence shatters when supernatural events entangle her. The ghost of a murdered girl—Haruka in the manga, Miko Onoyama in live-action—appears, demanding Asuka locate scattered body parts through apparitions and ominous messages. Failure to comply triggers a recurring time loop. Asuka and five classmates awaken at midnight on July 5th–6th within their school grounds. If they fail to find the dismembered remains before dawn, a blood-soaked entity called "The Red Person" brutally slaughters them.

Forced through relentless cycles, Asuka evolves from passivity into a determined leader, confronting fears and strategizing survival. Shared trauma bonds her with the other trapped students, forging previously absent camaraderie, mutual reliance, and collaborative problem-solving during nightly ordeals. Her childhood friend, Takahiro Ise, anchors emotional stakes. Within the loops, they reaffirm a forgotten promise symbolized by a badge from their past, revealing latent resilience. Asuka's resolve peaks confronting the entity fused with Miko's doll; she retrieves the final missing body part—the head—breaking the curse at great personal cost.

Post-curse, Asuka returns to her isolated reality with no conscious memory of the events. Yet, subtle triggers like rediscovering the badge hint at residual subconscious connections, rekindling recognition in Takahiro. A post-credits scene introduces ambiguity: a newspaper article alters the murder victim’s identity from Miko Onoyama to Asuka Morisaki, implying potential supernatural repercussions or cyclical curse reactivation targeting her directly.