A special government program has been launched to address the declining birth rates among demi-human races, which are suffering from a shortage of males. Under a so-called "assistance system," randomly chosen humans are mandated to mate with assigned partners—whether elves, sirens, or even dragons. Iris Thea Eaderlindt, an elven princess recognized for her open-mindedness and friendly demeanor toward humans, is transferred to Ark Metropolitan Academy. By coincidence, her new teacher has been selected as her mating partner. Anxious but resolved to fulfill her duty of securing her race's future, she begins engaging in sexual activities with him. To her surprise, Iris learns that her partner's ancestors were orcs, renowned for their exceptional sexual prowess. As more demi-human students join the class and discover the truth about their teacher's "side job," Iris finds it increasingly difficult to keep her partner's attention focused solely on her.