Nomura was an amateur champion at Nihon University, earning the amateur yokozuna title, and on entering professional sumo he was given makushita tsukedashi status, allowing him to begin at the bottom of the makushita division. He joined Dewanoumi stable, which was recommended to him by his cousin, a former wrestler at the stable named, and fought his first bout in March 1974. He had a losing record or make-koshi in his debut tournament, and was demoted to the sandanme division. However, five consecutive winning records in his next five tournaments saw him promoted to the jūryō division in May 1975, whereupon his changed his shikona or fighting name from Nomura to Dewanohana. He weighed barely more than 100 kilos and initially struggled as a sekitori, falling back to makushita for five tournaments. Upon his return to jūryō he won the division championship or yūshō with an 11–4 record. In November 1977 he was promoted to the top makuuchi division. Dewanohana was to spend 62 consecutive tournaments in the top division, compiling a record of 441 wins against 483 losses, with 6 injury absences. He received ten sanshō or special prizes, one for Outstanding Performance, five for Fighting Spirit and four for Technique. He earned two kinboshi or gold stars for defeating a yokozuna when ranked as a maegashira. His best performance in a tournament was in January 1985 when he was runner-up to Chiyonofuji with an 11–4 record in the first tournament held in the new Ryōgoku Kokugikan. His first appearance in the sanyaku ranks was at komusubi in November 1979, and he spent a total of 19 tournaments in sanyaku, 12 at komusubi and seven at sekiwake. He held the sekiwake rank for four straight tournaments in 1982 but failed to mount a challenge for ōzeki promotion, falling to 6–9 in September 1982. His last appearance in the sanyaku ranks came in September 1987 at the age of 36, where he could only score three wins against twelve losses. He retired just two tournaments later in January 1988, rather than face demotion to jūryō.
He has remained in sumo as an elder of the Japan Sumo Association, and works as a coach at Dewanoumi stable. His elder name ever since his retirement has been Dekiyama Oyakata. He was a judge of tournament bouts and joined the Sumo Association's executive board in 2014, managing the public relations department. He reached the mandatory retirement age for elders of 65 in 2016, but has been re-employed as a consultant for a period of five years on reduced pay.
Fighting style
Dewanohana was a yotsu-sumo wrestler who grappled rather than pushed, and was noted for his skill on the mawashi. His most common winning kimarite were yorikiri and uwatenage, and he also liked to employ the rare move komatosukui. Among his most memorable rivalries were with Wakashimazu and Takanosato.
