"Boku wa Misaki Tarou" centers on Misaki Tarou, a high school student who becomes entangled in a series of supernatural events after encountering a mysterious girl named Aya. Aya reveals that Tarou is the reincarnation of a powerful sorcerer from a parallel world, and his latent abilities begin to awaken. As Tarou grapples with his newfound powers, he discovers that his world is under threat from malevolent entities known as "Shadows," which seek to merge the human realm with their own chaotic dimension.

The narrative unfolds as Tarou forms an alliance with Aya and a group of other individuals who possess unique abilities tied to the parallel world. Together, they work to prevent the Shadows from breaching the barrier between dimensions. Tarou's journey is marked by his struggle to balance his ordinary life with his responsibilities as a sorcerer, as well as his growing understanding of his past life and its implications for the present.

Key characters include Aya, who serves as both a guide and a catalyst for Tarou's transformation; Kaito, a rival with a complex relationship to Tarou's past life; and Rina, a classmate who becomes an unexpected ally. The story explores themes of identity, destiny, and the consequences of wielding power, as Tarou and his companions face increasingly dangerous adversaries and uncover secrets about the parallel world and their own origins.

The plot is driven by a combination of action, mystery, and character development, with each arc revealing more about the overarching conflict and the characters' motivations. The series balances episodic encounters with the Shadows against a larger narrative that builds toward a climactic confrontation, blending personal stakes with the fate of both worlds.