Takeshiro is an ordinary, nondescript high school boy who has been rejected so many times in the past that he now goes out of his way to avoid any behavior a girl might misinterpret as romantic interest. Despite this defensive mindset, he cannot help noticing the girl who sits next to him: Akari Mitsuba. To everyone else, Mitsuba is a drab, forgettable presence—the kind of background character whose name classmates often struggle to remember. Yet, for reasons Takeshiro cannot fathom, this same unassuming girl repeatedly and aggressively makes advances toward him. She invades his personal space, whispers bold words in quiet moments, and reveals a startlingly forward side that clashes completely with her plain exterior.

Confused and wary, Takeshiro tries to suppress his natural attraction, convinced that he must be misreading her signals. But Mitsuba's pursuit is relentless and calculated. She uses her "invisibility" as camouflage, making her moves only when no one else is watching, so that Takeshiro becomes the sole witness to her true nature. As he struggles to keep his guard up, he finds himself increasingly flustered and drawn in by the gap between the shy surface she shows the world and the confident, almost predatory woman she becomes with him alone.

The story unfolds in an ordinary Japanese high school, with much of the tension taking place in quiet corners of the classroom, the library, or after-school spaces where the two are briefly out of sight of others. The central conflict is both internal and relational: Takeshiro must decide whether to trust his own feelings or continue protecting himself from potential hurt, while Mitsuba must navigate the risk of being rejected for the very boldness she uses to express her desire.

As the series progresses, the dynamic deepens. Mitsuba's younger sister Satori appears, concerned about her sister's behavior and confronting Takeshiro directly, which adds both comedic pressure and new complications. A mysterious handsome boy also begins showing interest in Mitsuba, testing Takeshiro's passivity and forcing him to confront his own growing possessiveness. Behind Mitsuba's extreme flirting lies a deep-seated insecurity: she has long felt invisible and unloved, and her aggressive approach is a desperate attempt to be seen and remembered by someone she truly cares about. Takeshiro's gradual realization that her "temptation" is not a game but a plea for genuine connection forms the emotional backbone of the narrative. The tone remains lighthearted and awkwardly romantic, driven by the comedic contrast between Mitsuba's plain persona and her audacious actions.