the kuroko serve many of the same purposes as running crew. They move scenery and props on stage, aiding in scene changes and costume changes. They will also often play the role of animals, will-o-the-wisps, or other roles which are played not by an actor in full costume, but by holding a prop. Kuroko wear all black, head to toe, in order to imply that they are invisible and not part of the action onstage.