"Tragedy on the G-String" is a psychological mystery anime that revolves around a series of interconnected events tied to a tragic incident. The narrative centers on a young man named Kotarou Tennouji, a former detective who becomes entangled in a complex web of crime, betrayal, and personal loss. The story begins with Kotarou investigating a string of murders linked to a mysterious violin piece known as "G-Senjou no Maou," which is said to drive its listeners to madness. As he delves deeper, Kotarou discovers that the murders are connected to a shadowy figure known as "Maou," a criminal mastermind who seems to have a personal vendetta against him.

The plot intertwines Kotarou's past with the present, revealing his complicated relationship with his adoptive father, a powerful and morally ambiguous businessman named Kyousuke Azai. Kyousuke's influence looms large over Kotarou's life, and their strained dynamic becomes a key element of the story. Kotarou's investigation leads him to cross paths with several key figures, including Usami Haru, a spirited and enigmatic girl who claims to be Maou's daughter. Haru's presence adds layers of intrigue and emotional complexity, as her motivations and true identity remain shrouded in mystery.

As the story progresses, Kotarou uncovers shocking truths about the people around him, including the possibility that Maou's actions are tied to a larger conspiracy involving Kyousuke's business empire. The narrative explores themes of revenge, morality, and the consequences of one's choices, with Kotarou forced to confront his own past and the role he may have played in the unfolding tragedy. The tension escalates as Kotarou races against time to uncover Maou's identity and prevent further bloodshed, culminating in a climactic confrontation that challenges his perceptions of justice and redemption.

The anime is structured as a tightly woven mystery, with each revelation building upon the last to create a sense of escalating tension. The characters are deeply flawed and morally ambiguous, with their actions driven by personal desires and hidden agendas. The interplay between Kotarou, Haru, and Kyousuke forms the emotional core of the story, as their relationships are tested by the weight of their shared history and the unfolding events. The narrative's intricate plotting and psychological depth make it a compelling exploration of human nature and the consequences of unchecked ambition and revenge.