"Magical Sempai" centers on a high school club dedicated to magic tricks, led by an enthusiastic but clumsy upperclassman known only as Sempai. Despite her passion for magic, Sempai’s performances are often marred by her extreme stage fright and frequent mistakes, leading to comedic mishaps. The story is narrated through the perspective of an unnamed male underclassman, referred to as Assistant, who stumbles upon the club and becomes Sempai’s reluctant helper. His pragmatic and often exasperated demeanor contrasts sharply with Sempai’s boundless energy and determination.

The narrative unfolds in a series of episodic chapters, each focusing on Sempai’s attempts to perfect various magic tricks. These attempts are frequently derailed by her nervousness, poor planning, or over-the-top enthusiasm, resulting in absurd and humorous situations. The Assistant, though initially indifferent, gradually becomes more involved in the club’s activities, often finding himself roped into Sempai’s elaborate schemes or forced to clean up after her failures. Despite her shortcomings, Sempai’s genuine love for magic and her unwavering optimism endear her to the Assistant and the small group of club members who occasionally join their antics.

The dynamic between Sempai and the Assistant forms the core of the series, with their interactions ranging from slapstick comedy to moments of subtle camaraderie. Sempai’s relentless pursuit of her dream, despite her lack of natural talent, serves as a recurring theme, while the Assistant’s growing involvement highlights his underlying respect for her dedication. The series balances its comedic tone with lighthearted character development, offering a mix of absurdity and charm as the characters navigate the challenges of their unconventional club activities.