"Oyasumi Jack the Ripper" is a manga series that blends historical fiction, mystery, and psychological drama. Set in Victorian London, the narrative revolves around Jack the Ripper, the infamous serial killer, but reimagines the character and the events surrounding the murders. The story introduces a young boy named Jack, who is adopted by a kind doctor after being found abandoned. Jack grows up in a loving environment, but his life takes a dark turn when he begins to experience disturbing visions and impulses tied to a mysterious entity known as "The Ripper."

As Jack matures, he struggles to reconcile his gentle nature with the violent urges that plague him. The Ripper, a manifestation of his darker self, compels him to commit gruesome murders, targeting women in the shadows of London's foggy streets. The series delves into Jack's internal conflict, exploring themes of identity, morality, and the duality of human nature. His adoptive father, Dr. Jonathan, becomes increasingly suspicious of Jack's behavior, leading to a tense dynamic between them as he tries to uncover the truth.

The narrative also introduces a detective named Arthur, who is determined to solve the Ripper murders. Arthur's investigation brings him into contact with Jack, creating a cat-and-mouse game that drives much of the plot. Alongside Arthur, a young woman named Mary plays a significant role. Mary, who has her own tragic past, becomes entangled in Jack's life, serving as both a potential victim and a source of emotional complexity for him.

The manga weaves together historical elements with supernatural and psychological undertones, creating a layered story that examines the origins of evil and the impact of trauma. The artwork complements the dark tone, with detailed depictions of Victorian London and expressive character designs that convey the emotional weight of the narrative. The series balances its exploration of Jack's psyche with a gripping mystery, keeping readers engaged as the story unfolds toward its climactic resolution.