Satan, also known in the series as Kai Sakurai, is like many of Shinjo Mayu's heroes: suave,
demanding, intensely sexual, and possesive. His love interest is Miu Sakurai.
Satan is summoned by Miu Sakurai, a high school student, who wishes to be noticed by her crush, Amamiya Shion. The price in return for her wish is Miu's virginity. When his initial spell does not work (Amamiya is a Christian), Satan turns himself into Kai Sakurai and alters the memories of everyone around them to make them believe that he is Miu's older brother.
As Miu's older brother, Kai tries to help her win Amamiya's love. But Miu begins to develop feelings for Kai and when Amamiya finally does confess to her, she rejects him for Satan (Kai) instead. Kai follows Miu to the church. They are both followed by Amamiya who is really the archangel Michael. Kai and Amamiya battle in the church, where Kai is wounded.
The next morning, Kai has altered everyone's memories again. He is no longer Miu's older brother, but now is her biology teacher at school. Soon, Satan is summoned back to hell by the half-demon Seera and he brings Miu with him. In hell, Satan and Miu consummate their relationship (several times) before returning to Miu's world.
Despite their intial bargain, Satan develops feelings for Miu and eventually asks her to become his wife in hell. It means that she will have to die, so he returns Miu to her home to think about her decision. Later, Satan discovers that Seera has plotted and succeeded in killing Miu. Satan kills Seera and runs to rescue Miu from heaven. Satan and Michael battle a final time. Though Michael could easily have bested Satan at the time, he recognizes the depth of Satan and Miu's love and allows them to return to hell. There, Satan and Miu are married.
Satan is summoned by Miu Sakurai, a high school student, who wishes to be noticed by her crush, Amamiya Shion. The price in return for her wish is Miu's virginity. When his initial spell does not work (Amamiya is a Christian), Satan turns himself into Kai Sakurai and alters the memories of everyone around them to make them believe that he is Miu's older brother.
As Miu's older brother, Kai tries to help her win Amamiya's love. But Miu begins to develop feelings for Kai and when Amamiya finally does confess to her, she rejects him for Satan (Kai) instead. Kai follows Miu to the church. They are both followed by Amamiya who is really the archangel Michael. Kai and Amamiya battle in the church, where Kai is wounded.
The next morning, Kai has altered everyone's memories again. He is no longer Miu's older brother, but now is her biology teacher at school. Soon, Satan is summoned back to hell by the half-demon Seera and he brings Miu with him. In hell, Satan and Miu consummate their relationship (several times) before returning to Miu's world.
Despite their intial bargain, Satan develops feelings for Miu and eventually asks her to become his wife in hell. It means that she will have to die, so he returns Miu to her home to think about her decision. Later, Satan discovers that Seera has plotted and succeeded in killing Miu. Satan kills Seera and runs to rescue Miu from heaven. Satan and Michael battle a final time. Though Michael could easily have bested Satan at the time, he recognizes the depth of Satan and Miu's love and allows them to return to hell. There, Satan and Miu are married.
