"Trickster" is a 24-episode anime series set in a world where a mysterious fog has rendered a boy named Yoshio Kobayashi immortal. After a failed suicide attempt, Yoshio encounters a group of young detectives known as the Boys' Detective Club, led by the enigmatic and brilliant Kogorou Akechi. The club operates out of the Hanasaki Detective Agency, solving various cases that often involve the supernatural or criminal underworld. Yoshio, who cannot die but also cannot live a normal life due to his condition, becomes entangled with the group after they discover his unique predicament.

The narrative explores the dynamic between Yoshio and the members of the Boys' Detective Club, particularly Akechi, who harbors his own secrets and a dark past. Akechi is driven by a desire to confront a criminal mastermind known as the Fiend with Twenty Faces, a figure who has eluded him for years. The Fiend with Twenty Faces is a cunning and elusive antagonist who orchestrates elaborate crimes, often targeting the wealthy and powerful. As the series progresses, the Boys' Detective Club finds themselves repeatedly clashing with the Fiend and his network of criminals, uncovering deeper layers of intrigue and danger.

Yoshio's immortality becomes a central focus, as it draws the attention of both the Fiend and other shadowy organizations. His presence within the Boys' Detective Club creates tension and moral dilemmas, as his condition raises questions about the nature of life, death, and humanity. The series delves into themes of identity, purpose, and the consequences of seeking immortality, while maintaining a balance between episodic detective cases and an overarching plotline.

The supporting cast includes members of the Boys' Detective Club, such as Kensuke Hanasaki, the agency's founder, and other young detectives who contribute their unique skills to solving cases. Each character has their own motivations and backstories, which are gradually revealed as the series progresses. The interplay between the characters, particularly Yoshio and Akechi, drives much of the emotional and narrative tension.

"Trickster" combines elements of mystery, action, and psychological drama, weaving together a story that explores the complexities of its characters and the world they inhabit. The series builds toward a climactic confrontation with the Fiend with Twenty Faces, while also addressing the personal struggles and growth of its protagonists. The narrative remains grounded in its exploration of human emotions and relationships, even as it ventures into the realm of the supernatural and the extraordinary.