The last day of school on an idyllic Okinawan island is abruptly turned into an unimaginable nightmare. For a group of high school students, the euphoria of their graduation trip instantly dissolves when a strange and grotesque epidemic transforms people into bloodthirsty horrors.

Trapped on an island now overrun by monstrous creatures, these young people must fight for their survival. As chaos takes hold and violence erupts around them, they must find a way to escape this paradise turned hell, not knowing whom to trust and facing a threat that defies all logical explanation.

The only lesson left for them is how to survive.