Gankaku is the Shotokan name for the "Crane on a Rock" kata of the Karate martial art. The raised arms and single leg stance are indicative of a crane standing atop a rock and was developed to enable the use of two counter-attack moves at one time. This technique uses strong vertical and horizontal lines and so can be very powerful, but the use of both the arms and legs at the same time requires massive ammounts of balance and concentration that only higher dan grades can muster.