At first fighting under his real name, he took on the shikona of Mienoumi in July 1966, but did not adopt the Tsuyoshi given name until September 1976. After being personally trained by the new Dewanoumi Oyakaya, former yokozuna Sadanoyama, he developed his technique and was promoted to the jūryō division in March 1969, and makuuchi, the top division, in September 1969. In July of the following year, he reached the rank of komusubi, defeating two yokozuna (Taihō and Tamanoumi) and receiving his first prize for Outstanding Performance.
Initially competing as himself, he took on the ring name Mienoumi in July 1966, but didn't adopt the surname Tsuyoshi until September 1976. Under the guidance of the new Dewanoumi Oyakaya, a former yokozuna named Sadanoyama, he honed his skills and was promoted to jūryō division in March 1969 and makuuchi, the top division, in September 1969. He reached komusubi rank in July of the following year, defeating two yokozuna (Taihō and Tamanoumi) and earning his first prize for Outstanding Performance.