Rin Hashiba lives together with her grandpa. One fateful day, while offering a prayer to God at the temple, a demon named Char appears before her. Seeking the blood of a virgin, Char is lewd, mean, and quite full of himself. He may act high and mighty, but in reality, he's very loving and kind. Even though she knows it's forbidden, Rin's body and mind are bound to fall into the demon's clutches one day
The main character of this story, Rin lost her mother at a young age and was raised mostly by her grandpa. Often lonely as a child, with only her Grandpa around, she befriended Shou, who she is now deeply in love with. She's somehow developed a reputation for sleeping around with guys despite being a virgin.
The demon king of Avalon, Char is sadistic and arrogant. In his world demons and humans despise each other and are seperated by a giant barrier. Char, who is himself half demon, dreams of uniting both sides and creating peace in his kingdom. Although he is at first dismissive of Rin, a 'mere human', he soon finds himself drawn to her.
Rin's childhood friend, Shou comes from a wealthy family and has many of admirers. After taking up a position at Rin's school she confesses her love for him, but he turns her down. However, that doesn't mean he's not interested...