Tamanoumi Masahiro

Tamanoumi had needed an appendectomy since at least July 1971, but he felt the responsibility of a yokozuna's duties and had not wanted to withdraw from the September 1971 tournament. After competing there taking painkillers and remarkably managing a 12-3 record, he went into hospital only after being an attendant at Taihō's retirement ceremony on October 2. Due to the delay in having the operation he was on the brink of peritonitis. The procedure seemed to have gone well and he was due to leave hospital on October 12, but on the morning of the 11th he collapsed and could not be saved. It emerged he had suffered a pulmonary embolism. He was only the fourth man in history to die whilst an active yokozuna. Kitanofuji was a good friend of Tamanoumi as well as a rival and was shocked by his death. He was just 27 years old and considered to be in his prime and likely to have won many more championships had he lived. In his last seven tournaments he had won four and been runner-up in the other three, and had lost only nine out of 105 bouts. His winning percentage as a yokozuna was .867, second only to Futabayama in the 20th century, and he gave away only three kinboshi in that time.

Upon reaching yokozuna Tamanoshima changed his ring name to Tamanoumi Masahiro, taking his coach's old shikona surname. His first tournament championship as a yokozuna came in September 1970 and he followed it up with another victory in November, defeating Taihō in a playoff. In July 1971 Tamanoumi won his sixth and final championship, his first with a perfect 15–0 record.

He began his professional sumo career in March 1959, using the shikona, or ring name, surname Tamanoshima (玉乃嶋). In 1962 his coach, Tamanoumi Daitaro, set up his own Kataonami stable and Tamanoshima joined it. He reached the top makuuchi division in March 1964. In May 1964, he changed the spelling of his shikona surname to 玉乃島. In 1965 a change in the rules meant that wrestlers from the same group of stables could meet each other in tournament competition, and Tamanoshima defeated Taihō in their first official match. He was promoted to sumo's second highest rank of ōzeki in November 1966 at the age of 22. At first, he was unable to reach a score in double figures at ōzeki rank, but his results began to improve significantly from November 1967. In May 1968, after three runner-up performances in a row, he finally captured his first yūshō, or tournament title, with a 13–2 record. The Yokozuna Deliberation Committee decided against promotion to yokozuna after this result due to the absence of both Taihō and Kashiwado from the tournament and his two losses to low-rankers in the first week. His second title came in September 1969. In November 1969 he posted a 10–5 record, and in January 1970 he took part in a playoff for the title with fellow ōzeki Kitanofuji. Tamanoshima lost the match, but after the tournament both Kitanofuji and Tamanoshima were promoted to the yokozuna rank. With Kashiwado already retired, and Taihō soon to follow, the two ushered in a new Kita-Tama era.

Tamanoumi Masahiro (Japanese: 玉の海 正洋, February 5, 1944 – October 11, 1971) was a Japanese professional sumo wrestler from Aichi. He was the sport's 51st yokozuna. Making his professional debut in 1959, he reached the top makuuchi division in 1964. He won six tournament championships and was runner-up in 12 others. Earlier in his career he also earned six special prizes and four gold stars. He was promoted to yokozuna simultaneously with his friend and rival Kitanofuji in January 1970 and the two men represented the dawning of a new era after the dominance of Taihō. He died suddenly in October 1971 after a delayed appendectomy.