In the remote and isolated island of Ushihi Island, the population faces a unique challenge. Their gene pool has become so insular that they require an outsider’s DNA to maintain their population. Seiichi, a dissatisfied teacher with a hidden gift, is invited by the island’s chief to assist with this issue.
However, Seiichi’s task is not a simple one. The island’s women have evolved to give birth just one week after conception, and they take great pleasure in winning over a man and bearing offspring. To aid in the stability of the island’s population, Seiichi is tasked with impregnating every woman on the island.
As Seiichi begins his work, he meets Konomi Tachibana, a vivacious and alluring island girl who works at a guest home. Konomi is eager to fulfill her duties as a woman and is confident that Seiichi will find her attractive. Her carefree personality and desire to have at least five children make her the perfect candidate for Seiichi’s task.
As Seiichi stays at the guest home, Konomi becomes increasingly infatuated with him, and her behavior becomes increasingly erratic. Will Seiichi be able to complete his task, or will Konomi’s growing feelings for him complicate matters?
This series is an original animation based on the manga created by studio Torudaya.