[7] In August 2014, he participated in the Openweight competition at the Sumo World Championships held in Taiwan and finished third, behind Ukrainian wrestler Oleksandr Veresiuk and Mongolian Baasansuren Turbold, who won that year's tournament.

[6] In May 2021, he participated to the 70th All Japan Sumo Championships at the Ryōgoku Kokugikan and became amateur-yokozuna after defeating Kindai University's Kanzaki Taiga in the final, again qualifying for the makushita tsukedashi system.

[14] In October of the same year, he participated in the National Athletic Meet in Ōtawara and won the amateur-yokozuna title for the second consecutive time in this tournament.

[16] In March 2023, Nakamura made the decision to become a professional wrestler (rikishi) by joining Nishonoseki stable under the guidance of former yokozuna Kisenosato.

[17] Before bestowing Nakamura his shikona, Kisenosato, with his former stablemate Wakanosato as intermediary, obtained permission for its use from Ōnosato Mansuke's family, who still reside in Aomori Prefecture.

[21] On the announcement of Ōnosato's debut as a professional wrestler, his former coach at Niigata Kaiyo High, Tetsuya Tōmi, declared his satisfaction, compared him to "a Shohei Ohtani of sumo", and said that Nakamura had the potential to become the monster of the new era (新時代の怪物).

[22] On the occasion of his passage to the new apprentice examination, Ōnosato, obliged to comply with professional wrestlers dress rules, received an obi belt that his master had used.

[23] Having received the Japan Sumo Association approval to compete, Ōnosato began his career at the rank of makushita tsukedashi 10.

[24] Nonetheless, Ōnosato finished the tournament with a score of 6–1, missing out, however, on promotion directly to the jūryō division, which some observers had been expecting.

[27] When the rankings for the September tournament were announced, however, it was confirmed that Ōnosato's score was sufficient to promote him to jūryō, professional sumo's second-highest division.

This promotion, acquired at the same time as stablemate and NSSU senior classmate Takahashi, allowed Nishonoseki stable to simultaneously receive two new sekitori, and the first two raised by Kisenosato alone since he had become master in 2019.

[41] However, he maintained his position as one of the tournament's leading wrestlers by recording a sixth consecutive victory and a kachi-koshi on Day 9 against Meisei.

[43] Ōnosato then suffered two consecutive defeats on Day 11 and 12, at the hands of Ōzeki Hōshōryū and Yokozuna Terunofuji, virtually eliminating him from the title race.

[49] After his inaugural tournament in the top division, Ōnosato commented that he was grateful to have been able to learn from the san'yaku ranks despite suffering three consecutive defeats at the hands of the upper echelons.

[50] During the March tournament of the same year, Ōnosato remained in the group of wrestlers leading the championship during the first week (tied with Takerufuji) nevertheless recording a defeat on the seventh day against Ōnoshō.

[51] Ōnosato managed to keep himself in the title race on Day 9 by beating a san'yaku-ranked wrestler for the first time, defeating Sekiwake Wakamotoharu.

[10] On Day 10, Ōnosato lost his match against Takerufuji, leaving the latter alone at the top of the title race with a two-win lead over the rest of the competitors.

[55] The latter defeated Ōnosato for the second time in a row, although the championship was not at stake because an injured Takerufuji had already won a thirteenth victory to become the champion.

[61] Both also apologized again with regard to the previous September's drinking situation, with Ōnosato stating that he caused trouble to so many people and his stablemaster, and that the most important thing was for him to keep winning.

[62] On the opening day of the May 2024 tournament Ōnosato faced yokozuna Terunofuji and scored an upset victory over his top-ranked opponent by sukuinage ("beltless arm throw").

[3][69] The day after winning the Emperor's Cup he told reporters at Nishonoseki stable: "I'm happy to have won the championship, but my final goal is not here.

[76] At the end of the tournament, Ōnosato secured both his promotion to the second-highest rank in professional sumo and the championship by defeating the two participating ōzeki, Kotozakura and Hōshōryū, on days 13 and 14 respectively.

[79][80] With his victory over the two ōzeki, the press echoed that Ōnosato now represented a new elite and dominant wrestler in the professional world, also raising expectations that he would become the 74th yokozuna in the history of the sport.

[82][83][84] Following the Sumo Association's approval, elders Dewanoumi (former maegashira Oginohana) and Hanaregoma (former sekiwake Tamanoshima) delivered the news to Ōnosato at his stable in Ibaraki Prefecture.

In formally accepting the promotion, Ōnosato said that he would continue to devote himself to the way of sumo, striving to become a yuiitsu-muni (唯一無二, 'one-of-a-kind' or 'unique') wrestler who does not tarnish the ōzeki rank.

The two often go to restaurants together during tournaments, and Ōnosato making fun of Shirokuma's ring name by repeatedly calling him "polar bear-san".

[94] On 6 February 2024, Ōnosato was part of a delegation of wrestlers from Ishikawa Prefecture sent after the 2024 Noto earthquake (along with Endō, Kagayaki and former Tochinonada); charged with symbolically presenting Governor Hiroshi Hase with the sums raised during the January tournament and donations from the Sumo Association, since the presence of sumo wrestlers is considered a good omen.

[95] During his stay, he also paid a visit to the evacuation center that had housed his grandfather, receiving numerous messages of congratulations from the disaster victims for his recent sporting achievements.

[95][96] Sanshō key: F=Fighting spirit; O=Outstanding performance; T=Technique     Also shown: ★=Kinboshi; P=Playoff(s) Divisions: Makuuchi — Jūryō — Makushita — Sandanme — Jonidan — Jonokuchi Terunofuji (retired) Kotozakura Hōshōryū Ōnosato Wakamotoharu Daieishō Abi Wakatakakage Takanoshō Kirishima Tobizaru Atamifuji Gōnoyama Ōhō Shōdai Ura Hiradoumi Chiyoshōma Takayasu Ichiyamamoto Endō Mitakeumi Rōga Takarafuji Churanoumi Ōshōma Tamawashi Meisei Midorifuji Takerufuji Nishikigi Ōnokatsu Shōnannoumi Kotoshōhō Hokutofuji Kinbōzan Hakuōhō Kitanowaka Tamashōhō Kagayaki Nishikifuji Tokihayate