Toru Usui is a high school boy so devoid of presence that his classmates regularly fail to notice him. His lack of existence is so profound that even automatic sliding doors do not register his approach and refuse to open for him. In a school environment that treats him like a ghost, Usui has accepted his invisible status.

The arrival of transfer student Chika Mikage, a kunoichi or female ninja, upends this quiet existence. Unlike everyone else, Mikage immediately recognizes Usui not as a social outcast, but as a prodigy possessing a natural and unparalleled talent for stealth. Seeing his innate ability as the perfect foundation for a shinobi, she enthusiastically approaches him with a clear goal: to recruit and train him to join the world of ninjas.

However, Usui harbors his own unexpected dream, one that directly conflicts with Mikages plans for his future. He has no desire to become a stealth master; his ambitions lie somewhere far more ordinary or perhaps absurdly specific, creating the central comedic tension between the two.

The story unfolds as an everyday romantic comedy centered on this mismatched pair. A completely airy and oblivious high school boy who simply wants to live his life is pursued by a determined kunoichi who desperately wants to transform him into a ninja. Their interactions form the core of the series, which is serialized under the DRE Comics label and explores the humor that arises when ninja traditions clash with modern high school life. The narratives main arcs likely focus on Mikages increasingly creative and elaborate attempts to stealth-train a completely unwilling Usui, his accidental uses of his natural skills for mundane purposes, and the gradual development of their relationship amidst these ninja-themed antics.