Monster is a psychological thriller anime series based on the manga of the same name by Naoki Urasawa. The story follows Dr. Kenzo Tenma, a brilliant neurosurgeon whose life spirals into chaos after he saves the life of a young boy named Johan, who grows up to become a notorious serial killer. As Tenma embarks on a quest to stop Johan, he confronts moral dilemmas and the darkest aspects of human nature.