History tells that this kata originated in the late 18th century from a chance encounter between a Chinese military officer, Kushanku, living in Okinawa and a young martial artist named Sakugawa. Sakugawa tried to push Kushanku off a bridge into a river, only to be stopped easily. Sakugawa ended up studying with Master Kushanku and eventually developed the kata from techniques he had learned from him and from his first teacher, Takahara. He named the kata Kusanku.
Master Sakugawa passed on Kusanku to Master Bushi Matsumora who, in turn, taught Master Kyan—Master Shimabuku's teacher of Shorin-ryu.
Kusanku utilizes deception and evasive techniques in teaching combat in limited light situations. Along with Sunsu, it is the longest of our hand kata.