"Mikagura Detective Agency" centers around Mikagura Academy, a prestigious school with a unique system where students form clubs to compete in battles for resources and prestige. The story revolves around Eruna Ichinomiya, a cheerful and energetic first-year student who joins the academy after being inspired by a brochure featuring the beautiful Seisa Mikagura. Upon arrival, Eruna discovers that Seisa is the leader of the Mikagura Detective Agency, a club that investigates mysterious occurrences within the school.

Eruna quickly becomes infatuated with Seisa and decides to join the agency, despite having no prior experience or skills relevant to detective work. The club’s members include Shigure Ninomiya, a calm and analytical second-year student, and Otone Fujishiro, a shy but talented artist. Together, they tackle various cases, ranging from uncovering hidden secrets within the school to solving supernatural phenomena tied to the academy’s history.

As the series progresses, the narrative delves into the personal backgrounds of the main characters, revealing their motivations and struggles. Seisa’s aloof demeanor hides a deeper connection to the academy’s mysteries, while Shigure’s past and Otone’s insecurities add layers to their personalities. Eruna’s relentless optimism and determination often serve as the driving force behind the group’s efforts, helping them overcome challenges and grow closer as a team.

The plot intertwines episodic detective cases with an overarching mystery involving the academy’s origins and the true nature of the club battles. The series balances lighthearted moments with more serious themes, exploring friendship, self-discovery, and the pursuit of one’s passions. Through their investigations, the members of the Mikagura Detective Agency uncover truths about themselves and the world around them, ultimately shaping their futures within the academy.