"My Idol Sits the Next Desk Over!" centers on the life of Aoi Hinata, an ordinary high school student who discovers that his classmate, Yuzuki Hoshino, is secretly a popular idol. Yuzuki, known by her stage name Yuzu, is a member of the idol group "Starlight Melody," but she hides her identity at school to maintain a normal life. Aoi accidentally learns her secret when he overhears her practicing a song in an empty classroom. Despite his initial shock, he promises to keep her secret, and the two gradually form a close bond.

The narrative explores the challenges Yuzuki faces in balancing her dual life as an idol and a student. Her rigorous schedule, public scrutiny, and the pressure to maintain her image often leave her exhausted and isolated. Aoi becomes a source of support, offering her a sense of normalcy and friendship that she struggles to find elsewhere. Their relationship evolves from classmates to confidants, with Aoi often helping Yuzuki navigate the complexities of her idol career while ensuring her secret remains safe.

The story also delves into the dynamics of Yuzuki's idol group, highlighting the camaraderie and rivalries among its members. Other characters, such as Aoi's childhood friend Rina and Yuzuki's manager, play significant roles in shaping the plot. Rina, unaware of Yuzuki's secret, becomes suspicious of her growing closeness to Aoi, adding a layer of tension to the story. Meanwhile, Yuzuki's manager is constantly on edge, trying to protect her from scandals and overzealous fans.

As the series progresses, Yuzuki's idol career faces various challenges, including intense media scrutiny, fan expectations, and the pressure to perform. Aoi's unwavering support helps her confront these obstacles, but their relationship is tested by the demands of her profession and the need to keep their connection hidden. The manga balances lighthearted moments of school life with the more serious themes of identity, ambition, and the sacrifices required to pursue one's dreams.

The characters are well-developed, with Yuzuki's vulnerability and determination contrasting with Aoi's grounded and empathetic nature. Their interactions are central to the story, showcasing the growth of their relationship amidst the complexities of Yuzuki's idol life. The manga effectively blends elements of romance, comedy, and drama, creating a compelling narrative that appeals to fans of both slice-of-life and idol-themed stories.