Hiroki Koizumi is a high school student who sinks into a severe depression and deep lethargy after his girlfriend vanishes. This state causes him to rebuff the persistent affections of his childhood friend, Aimi Koenji. He endures public humiliation from his teacher, Mr. Iwata, and offers no resistance to his bullies, relying on Aimi to intervene on his behalf. His depressive condition is characterized as unnatural, a symptom of the demonic forces corrupting the school. His story reaches its conclusion when he recognizes his true feelings for Aimi at a pivotal moment. He makes a heroic sacrifice by stepping into the monstrous form Aimi has become and professing his love, an act which results in their souls uniting, ascending, and ultimately destroying the demonic threat.