Ouka, a transfer student at Ark Academy. She is the childhood friend of his homeroom teacher and the princess shrine maiden who heads the demon clan. Ouka used to be as attached to him as a little sister, but upon their reunion after several years, she witnesses him and his student having sex, and her rage explodes. She seals the teacher's penis with demonic magic. "You're tainted, brother." The teacher, unable to have sex anymore because of Ouka's hand. He tries to persuade her, but Ouka remains stubborn. So he resorts to his last resort... A sweet moan, unimaginable from her dignified demeanor. Her bountifully grown breasts, freed from her solemn Japanese attire. As a childhood friend and teacher, he gently unravels Ouka's heart, which had been suppressed in order to become the head of the clan. They were supposed to be having a sex marathon while the demons were away... but that didn't happen. A sudden turn of events that would bring tears to even a demon's eyes!? With even more extreme fan service than usual, it's like giving a demon a club ♡