Kainoyama Isamu (born Isamu Irii; June 28, 1940 – July 5, 1997) was a sumo wrestler from Ryūgasaki, Ibaraki, Japan. He made his professional debut in May 1955, and reached the top division in January 1961. His highest rank was sekiwake. Upon retirement from active competition he became an elder in the Japan Sumo Association under the name Onogawa. He left the Sumo Association in September 1971.