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.

After successfully clearing a vampire nest and rescuing the humans held captive, Yūichirō's party sets for the human base in Shinjuku, unaware that the vampires are attacking there. Upon arriving, they come across one of the vampire nobles, and find themselves at mercy of his overwhelming power.