effektjes's comment: It's a Japanese modern-dance form introduced in the west in the '70s. It's an expressionistic way of dancing and means 'dance of the darkness' or of the 'dark soul' (ankoku butoh). In the '30s it came up, being a a mixture of different danceforms of Japanese and western origin. It has classical japanese theatre roots, and knew influences from Wigmans Ausdrucktanz. Also Artaud was a big influence on renovating japanese theatremakers.