Noroko is one of the main characters from the M.U.G.E.N game, The Black Heart. She is a ghost who lies dormant within an ancient Japanese doll which is currently owned by an antique collector. She is heavily based on Japanese horror films and folklore, taking inspiration from the Onryo ghosts: typically female spirits who suffered violent deaths that now seek vengeance upon the living.
When the king of the other world is murdered and his heart is ripped out, the power emanating from it was strong enough to awaken Noroko who escapes the doll and kills the collector. Noroko travels through the worlds searching for the heart currently in possession by Final hoping its power can end her suffering and grudge, which is so powerful it drives her to attack and kill anyone she comes across.
In M.U.G.E.N, Noroko has been made by Andrés Borghi. While Noroko was initially exclusive to The Black Heart, she was released for regular M.U.G.E.N some time after the game's initial release.