Attacked by vampires at a club, nineteen-year-old En survives after being bitten and turning into a vampire himself. He is then found by Ichii, a vampire from the organization 'FANGS' who becomes his guardian. To satisfy the vampires' urge to suck blood, the organization encourages a 'pairing system' where two vampires agree to support one another. At his first pairing party, En attracts a lot of vampires due to his status as a 'virgin', and thus declares in a panic that he will become Ichii's pair…?!