Kyutaro Horikita, a reserved and diligent student, works as a cleaner at Kurokado High School, a prestigious institution with a dark secret. Beneath its polished exterior, the school harbors a supernatural dimension where negative emotions manifest as dangerous entities called "Bees." Kyutaro is no ordinary cleaner; he is a "Sweeper," tasked with purging these Bees and cleansing the hearts of those they infest. His work is part of a larger, mysterious organization dedicated to maintaining balance between the human and spiritual realms.

Fumi Nishioka, a cheerful and resilient transfer student, enters Kyutaro's life when she stumbles upon the Sweeper's hidden world. Despite her seemingly ordinary demeanor, Fumi possesses a unique ability to sense and interact with the Bees, making her an unexpected asset to Kyutaro's mission. As the two form an unlikely partnership, they uncover Fumi's mysterious past, which is deeply intertwined with the supernatural forces they combat. Her memories are fragmented, and her connection to the Bees hints at a greater role in the spiritual conflict.

The narrative explores the psychological and emotional struggles of the characters they encounter, as each Bee represents a person's inner turmoil, trauma, or unresolved pain. Kyutaro and Fumi work together to confront these manifestations, often delving into the personal histories of those affected. Their efforts reveal the complexity of human emotions and the consequences of suppressing or ignoring them. The story balances supernatural action with introspective moments, highlighting the importance of confronting one's inner demons.

As the series progresses, the relationship between Kyutaro and Fumi deepens, blending elements of camaraderie, trust, and mutual growth. Their partnership is tested as they face increasingly powerful adversaries and uncover the truth about Fumi's origins. The narrative builds toward a climactic confrontation with the forces that seek to exploit the Bees for their own gain, forcing the protagonists to confront not only external threats but also their own vulnerabilities.

"QQ Sweeper" combines elements of fantasy, mystery, and psychological drama, creating a compelling exploration of human emotions and the supernatural. The interplay between the characters' personal journeys and the overarching plot drives the story forward, offering a blend of action, introspection, and emotional resonance. The series maintains a focus on the themes of healing, self-discovery, and the power of human connection, making it a distinctive entry in the supernatural genre.