Takuya Seo is an otaku and a loner high school student who harbors a secret passion for Kirarimon Pets, an anime series aimed at young girls. Ashamed of this interest, he keeps it hidden from his classmates. He sits in front of two popular and fashionable gyaru, Kotoko Ijichi and Kei Amane, who belong to a different social world he refers to as a separate caste, leading him to believe they could never have anything in common.

The story begins when Takuya accidentally drops his eraser, one featuring a character from his favorite show. This leads to a conversation where he overhears the two girls discussing the series. When Takuya corrects them on a detail, Amane, who initially claims not to be a fan, demonstrates an in-depth knowledge of the anime that suggests otherwise. This incident reveals that beneath her cool and reserved exterior, Amane is a fellow otaku hiding the same passion. Kotoko, in contrast, is outgoing and cheerful, and her non-judgmental curiosity about Takuya's hobby helps break down his defensive walls.

The series is set in a contemporary Japanese high school, exploring the social hierarchies and anxieties surrounding niche hobbies. The narrative follows the three as they form an unexpected and secret bond over their shared love for Kirarimon Pets, communicating through text messages and meeting in private to avoid the scrutiny of their peers. As the story progresses, their friendship deepens, with Kotoko acting as a bridge to pull Takuya out of his shell while Amane becomes his confidant for their mutual obsession. Notable narrative arcs include the trio attending a merchandise release event, sleepovers where they marathon the anime, and the gradual development of romantic tensions, creating a love triangle that threatens the established dynamic of their close-knit group. The central conflict revolves around the fear of social ostracism and the characters learning to reconcile their public personas with their private passions.