Sosui Ichikawa (市川 素水; August 29, 1924 - March 7, 2005), was a Japanese martial artist born in Ueno, Tokyo, Japan who was the 4th Sōke of the Zen Nihon Goju-Ryu Karate-do Renmei (全日本剛柔流空手道連盟) and founder of the Sosuikan (素水館). He would teach Goju-Ryu karate while still doing his research and development. Ichikawa's studies were often focused on the Bubishi (武備志), and would ultimately come to write his texts, the Kōshu-do (交手道) and other documents. Sosui Ichikawa was accepted as Hanshi (範士), Jūdan (十段) in 1983 by the Okinawan Karate-Do Renmei.