Hirai Momo was once an ordinary girl until one fateful night in which she almost lost her life to a vampire. Saved by a mysterious woman, she was able to survive but lives the rest of her life seeking vengeance on the one who has made her sick. She is not a vampire herself, the woman who saved her made sure of that, but the attack that almost ended her life left her with a disease that makes it impossible for her to venture into sunlight without consequence. She becomes a member of an organization that hunts and kills vampires. There are only two things Momo wants to accomplish before dying: killing the vampire that almost ended her life and meeting the one that saved her life, one more time.

        Myoui Mina is a vampire that is neither good nor evil. She does not believe in killing needlessly and does not wish to create any more beings like herself. She does however feed on humans but never changes them and never kills them. She's been at it so long that she may be the only vampire capable of such a thing. She doesn't like what she is but there's nothing she can do to change it (though she has tried in the past) and so she has learned to accept it. With a diverse knowledge of cures and curses, she is of valuable use to the organization at which Momo works.

        However, Momo does not see it that way. She loathes all vampires and is immediately hostile towards Mina when they are paired up on a mission to take out a vampire terrorizing the streets of Osaka.