The first-year high school student Kurogane Taito is a disillusioned youth, and no longer believes that hard work and effort will be compensated. Now, he simply exists as the days pass him by.
However, there is something that he has forgotten. A stolen memory of a girl, a pact, and a curse: nine years ago, the young Taito met Saito Himea, an elder vampire, and made a pact with her.
Now, as Taito's memories slowly return, after an accident he should not have been able to survive, he will remember the girl who had been kidnapped and kept imprisoned for the past nine years, waiting for him to free her.
(translated and adapted from the official site by Cranston)