Johan Liebert is the titular "monster" of the series and the central mystery driving the entire narrative. Comparisons to him have ranged from brutal to biblical—he's been called the next Hitler, the devil incarnate, and worse. But his story begins with a debt: as a child, he was shot in the head and left for dead until Dr. Tenma saved his life. That act of mercy shaped everything that followed, giving Johan a twisted sense of gratitude toward the man who rescued him.
Over the years, Johan reinvented himself constantly, living under false names in different cities. He's frighteningly intelligent and possesses an almost supernatural charisma—gifts he weaponizes without hesitation to manipulate and corrupt anyone around him. His cruelty often seems purposeless, driven by a pure desire to inflict suffering and watch things fall apart. Younger versions of Johan openly stated his goal: to be the last person standing when the world ends. Though by the story's conclusion, he'd settled on something different.
What makes Johan particularly terrifying is how he functions as a catalyst for transformation. Monster explores the idea that ordinary people can become monsters themselves, and Johan—whether directly or from a distance—tends to be the spark. He doesn't just destroy people; he reveals and amplifies the darkness already inside them.
One consistent thread throughout his life is his attachment to his twin sister, Nina (also known as Anna Liebert). No matter what he's done or where he's gone, he refuses to abandon her. That bond is perhaps the closest thing he has to genuine feeling.
Content compiled by AnimeList.moe from publicly available sources.
