Being kind to girls is the most important thing to 17-year-old Iida Harunari. As the kind of guy to carry the bags of all the girls in his class with him to school each morning, those around him sarcastically called him the "ultimate gentleman Iida". One day, he encountered a beautiful girl with a strange aura, Kageura Sari, but he noticed a cursed-looking monster emerging from her body. Iida was going to hurry and flee, but wasn't something amiss...? He was cursed by the heroine?!