"Legend of the Pervert" centers on Hiroshi Tanaka, a socially awkward high school student whose life takes an unexpected turn when he discovers a mysterious artifact that grants him peculiar abilities. The artifact, known as the "Eros Stone," amplifies Hiroshi's latent desires, transforming him into a figure of both admiration and ridicule among his peers. The narrative explores Hiroshi's struggle to balance his newfound powers with the moral dilemmas they create, as his actions inadvertently affect those around him.

The story unfolds in a suburban Japanese town, where Hiroshi navigates the complexities of adolescence while grappling with the consequences of his abilities. His best friend, Yuki Nakamura, serves as a grounding force, often challenging Hiroshi's impulsive decisions. Meanwhile, Aiko Takahashi, a classmate with a sharp wit and strong sense of justice, becomes a key figure in Hiroshi's journey, as her skepticism about the Eros Stone leads to a deeper investigation into its origins.

As Hiroshi's powers grow, he attracts the attention of a secretive organization known as the "Order of Eros," which seeks to reclaim the artifact for its own purposes. The Order's enigmatic leader, Kaito Shimizu, views Hiroshi as both a threat and a potential ally, leading to a series of confrontations that test Hiroshi's resolve. The narrative delves into themes of self-discovery, responsibility, and the blurred lines between desire and morality.

Throughout the series, Hiroshi's relationships with Yuki and Aiko evolve, highlighting the impact of his choices on their lives. The story also introduces secondary characters, such as the mischievous Rika Sato and the stoic Kenjiro Matsuda, who add depth to the narrative by providing contrasting perspectives on Hiroshi's actions. The plot builds toward a climactic showdown between Hiroshi and the Order of Eros, culminating in a resolution that forces Hiroshi to confront the true nature of his desires and the legacy of the Eros Stone.