"Satsujin Kippu wa Heart-iro" is a mystery-thriller anime that revolves around a series of interconnected murders tied to a unique and sinister concept: the "Murder Tickets." These tickets, distributed anonymously, grant their holders the right to commit a single murder without legal consequences. The narrative explores the moral, psychological, and societal implications of this system, as well as the chaos it unleashes.

The protagonist, a young detective named Haruto Asakawa, becomes embroiled in the investigation after a close friend becomes a victim of the Murder Tickets. Asakawa is driven by a personal vendetta and a desire to uncover the truth behind the tickets' origins. His investigation leads him to cross paths with a diverse cast of characters, including other ticket holders, victims, and shadowy figures orchestrating the system. Among these is Rina Fujisaki, a morally ambiguous woman who wields a ticket and becomes both an ally and a potential threat to Asakawa's mission.

The plot unfolds through a series of interconnected arcs, each focusing on different individuals who possess or are targeted by the Murder Tickets. These arcs delve into their motivations, fears, and the consequences of their actions, painting a complex picture of human nature under extreme circumstances. Asakawa's pursuit of the truth gradually reveals a larger conspiracy involving powerful entities manipulating the system for their own gain.

The anime balances its central mystery with intense psychological drama, exploring themes of justice, morality, and the fragility of societal order. The tension escalates as Asakawa uncovers deeper layers of the conspiracy, culminating in a high-stakes confrontation with the masterminds behind the Murder Tickets. The story concludes with a resolution that ties together the fates of the main characters while leaving lingering questions about the nature of justice and the human capacity for both good and evil.