Mukuro

軀

Mukuro is one of the Three Kings of Makai. She has been a sex slave since birth, and on her seventh birthday, she decided to pour acid on her body so that her master would abandon her. Once free, she replaced the burned right side of her body with mechanical parts and masked herself to hide her womanly status. In the following centuries, she became stronger and stronger, feeding her powers with the hate derived from her traumatic childhood, and slowly built a kingdom until she became strong enough to face the Makai Lord Raizen and start a war against him.
She was saved from being consumed by hatred by finding Hiei's lost Hirui stone, which had the power to calm her soul. Later, she summoned Hiei to be her ally in the Three Kings war, and she developed a deep bond with him because they had both experienced deep hate and a traumatic childhood.
During the Makai tournament in the anime, she fought Hiei and won, but he managed to break the hard chains that she had on her wrists since the time of her slavery, a symbolic way to free her from her past. In the manga, Hiei does the same thing by capturing her abusive master and removing a mental conditioning that prevented her from trying to kill him.