"Babylon" is a psychological thriller anime that explores themes of morality, justice, and the nature of evil within a politically charged narrative. The story is set in the fictional Shiniki district of Tokyo, where a new administrative zone is established to test experimental laws and policies. Seizaki Zen, a public prosecutor, is assigned to investigate a pharmaceutical company suspected of illegal clinical trials. During the investigation, he uncovers a series of mysterious deaths linked to the company, leading him to Ai Magase, a woman with a chilling aura and a connection to the crimes.

As Seizaki delves deeper, he discovers that Ai Magase is not only involved in the deaths but also possesses an uncanny ability to manipulate people into committing suicide. Her actions spark a broader societal debate about the definition of evil and the limits of the law. The narrative takes a dramatic turn when the Shiniki district declares independence from Japan, led by its charismatic and enigmatic governor, Kujiin Shin. Shin introduces radical policies, including the legalization of suicide, which further destabilizes the region and challenges Seizaki's sense of justice.

The plot intensifies as Seizaki and his allies attempt to uncover the truth behind Ai Magase's motives and her connection to Shin. The story examines the ethical dilemmas surrounding life, death, and the role of government in regulating morality. Key characters include Seizaki Zen, the determined and morally driven prosecutor; Ai Magase, the enigmatic and manipulative antagonist; and Kujiin Shin, the ambitious and morally ambiguous governor. The series weaves a complex web of intrigue, exploring the psychological and philosophical implications of its central conflicts. The narrative builds toward a tense and thought-provoking conclusion, leaving viewers to grapple with the moral questions it raises.