Bitten by a vampire at a club, nineteen-year-old En barely survived. Taken under the wing of Ichii - a member of the health and welfare division of the vampire rights organization known as FANGS - En learns he's to be taught about this new 'world' he must survive in. In order to control the urge to suck blood and attack innocents, FANGS established a 'pairing system,' where two vampires support one another with regular meals. As a young, virginal vampire, En is highly sought after by many senior vamps. That is, until he declares his intention to pair with his guardian, Ichii.