An epidemic of unknown origin strikes mankind, killing all adults and rendering the youngsters at the mercy of the vampire kind. Four years later, Yūichirō Hyakuya and his friends make a daring attempt to escape from the vampires, unaware that a mortal trap awaits them.

Yūichirō learns that one of his schoolmates was possessed by a demon and decides to confront him not only in order to save him but to make a contract with the demon and obtain his power. However, he soon learns that subduing the demon will not be such an easy feat.

Yūichirō and Shinoa get separated from the others and after taking a wounded soldier to be treated, they regroup to assist Guren's party. In the occasion, Yūichirō and Mikaela finally meet again.

Mikaela attempts to escape, taking Yūichirō with him. However, seeing his friends at the mercy of the vampires, Yūichirō goes out of control when a dreadful power emerges from him, threatening allies and foes alike. Shinoa manages to stop him but he falls unconscious.

Shinoa spars against Guren before visiting Yu in the library. She tells him about turning humans into vampires. Then, Kureto Hiragi summons Yu to ask him about a vampire spy while torturing Kimizuki and Yoichi to make him tell the truth. Afterward, Yu asks Guren about it and asks if Mika would also be useful to him. In Sanguinem, Mika starves for blood and Ferid recommends halting his growth there. A child offers his blood to Ferid, and Ferid tempts Mika to drink the boy's blood but Mika refuses. Ferid then invites Mika to the Progenitor Council meeting.

When the Shinoa squad arrives late, they realize just how serious this mission is for Guren. Knowing this is an impossible mission where many will die, Guren puts his emotions aside and orders his men to not necessarily survive, but to win.