Japan has been invaded by the secret society Black Devil, which aims to overthrow the nation. Top professional hero Mineta Minemizu spends his days fighting the organization’s forces to protect the peace. But when Black Devil suddenly introduces a complete two‑day weekend system, the heroes are forced to adopt the same work schedule. Minemizu, a workaholic, is thrown into chaos by his two blank days—and that chaos deepens when he confronts the enemy leader. On the throne he expects a fearsome villain, but instead finds a tiny girl named Nikon, who is revealed to be the next leader of Black Devil. After wrestling with the fact that she is only a child, Minemizu chooses not to defeat her but to protect her. What follows is a holiday beginner comedy in which the top hero, utterly unprepared for fatherhood, fumbles through raising the young girl while the comical activities of Black Devil continue in the background. Ken Koyama, author of Seiri-chan, presents a story about a man learning to balance his professional duty with unexpected parenthood, and about a reclusive, clumsy yet adorable child who might be the key to the organization’s future.