Sara Tateshina, a new female teacher in charge of religious studies, has been transferred to St. Moses Academy. Mayu, a student at the school, silently passes in front of Sara, as if attracted by something. Kojiro, a senior who is worried about Mayu and follows her, enters the dark basement beyond the vault door, which is forbidden to enter. Descending a long spiral staircase, Miku emerges from a coffin in an underground room filled with damp, musty air. Mayu raises his hand suspiciously, and his uniform is swept away with no expression on his face.