Weak, bullied, and pessimistic about life, that's Setsuna Kashiwagi. On the verge of jumping off a bridge, a mysterious man appears behind him and offers the contract "10 million yen in exchange for your life in a year." Skeptical at first, he accepts. Waking up the next morning, thinking it was just a dream, he notices 2 beautiful women sitting beside him. They are Kanna and Rena, Oni princesses here to claim his heart in a year.