"Remember how you said you wanted a younger sister?" Toujo Basara, a first year high school student, was caught off guard when his father suddenly brought up the topic. To make matters worse, his unusual father revealed that he was getting remarried and bringing back two stunning step-sisters from overseas. Little did Basara know, however, that Mio and Maria were actually a fledgling Demon Lord and a succubus. Basara nearly became Mio's servant, but due to a mistake, he instead becomes her master in a reverse contract. This contract leads to a range of scandalous situations for Basara, while Mio is sought after by rival demon and hero tribes. Thus begins the thrilling action-packed story of the most powerful contract holder and his desires.
