Transi is a smart girl who transfers to Pieta's class, a high school girl living an ordinary life. Transi has a constitution that triggers murders around her, and she is also a detective who solves the cases. Pieta falls in love with her and offers to be her assistant. As people around her die one by one, Pieta, the person closest to Transi, somehow stays alive.

This is a story of two girls who celebrate their own lives even if the world is dying.