Futabayama Sadaji (双葉山 定次, February 9, 1912 – December 16, 1968) was a Japanese professional sumo wrestler from Oita Prefecture. Entering sumo in 1927, he was the sport's 35th yokozuna from 1937 until his retirement in 1945. He won twelve yūshō or top division championships and had a winning streak of 69 consecutive bouts, an all-time record. Despite his dominance he was extremely popular with the public. After his retirement he was head coach of Tokitsukaze stable and chairman of the Japan Sumo Association.