Dr. Kenzo Tenma, a brilliant Japanese neurosurgeon working in Germany, is faced with a moral dilemma: operate on a young child who was shot in the head, or operate on the mayor who arrived later. He chooses to save the child, but this decision costs him his position and reputation. Years later, the child, Johan Liebert, emerges as a charismatic and dangerous sociopath responsible for a string of murders. Haunted by his past choice, Tenma dedicates his life to stopping Johan and uncovering the truth behind his dark origins, all while being pursued as the prime suspect in the murders committed by Johan.