A year ago while Siesta was still alive, a series of mysterious incidents occurred in which the human heart was severed. Siesta and Kimizuka realized that the incident was the work of Cerberus, a member of the secret organization SPES, and planned an ambush operation. Kimizuka, who was the bait, chased the figure that invaded the pitch-dark room. However, the figure who appeared was Hel, a girl who missed Siesta.