You're a human boy in a school where monsters are real, and you're falling for one so minor her only power is sticking to you when she's into you. Petoko doesn't have fangs or speed or magic, she has desperation, clumsiness, and the kind of earnest affection that turns a nothing ability into the most honest confession in the room. This is a show about loving someone who has nothing to offer but wanting to stick around anyway, and it finds the whole romance in that mismatch.
Oohashi Shingo attends an ordinary high school in a world where youkai have become everyday fixtures alongside humans. His classmates range from mild-mannered to genuinely monstrous, but none quite capture his attention like Fujimura Hatoko, a petopeto: a minor supernatural creature whose singular power is the ability to cling unwaveringly to whatever captures her affection. Unfortunately for Shingo, that affection is directed squarely at him. What unfolds is a comedy of escalating awkwardness as Hatoko's literal inability to let go creates constant chaos. Whether it's disrupting class, interfering with his daily routines, or landing him in increasingly compromising situations, her devoted attachment proves both endearing and utterly inconvenient. Caught between genuine fondness for the persistently clingy youkai and the practical nightmare of having her permanently attached, Shingo navigates a world where the line between romance and comedy blur completely. The series thrives on the simple premise: watch what happens when a creature designed only to stick around meets a boy she decides is worth sticking to, consequences be damned.