Early career

Wakamotoharu made his professional debut in November 2011 under the shikona, or ring name, Araonami (荒大波).^[9] In his first official tournament (honbasho) in January 2012, under the new shikona Goshi (剛士), he won the jonokuchi championship, or yūshō, with a perfect 7–0 record.^[10] In May 2017 he adopted the shikona of Wakamotoharu.^[10] In January 2019 he won the makushita division championship with an undefeated 7–0 score and was promoted to the jūryō division along Kiribayama.^[11] At the time of his first promotion to the jūryō division, he and Wakatakakage became the twentieth pair of brothers to achieve the status of sekitori in sumo history.^[12] Commenting on his promotion his master Arashio (former komusubi Ōyutaka) and his senior Sōkokurai expressed their reservations, with his master commenting that he had been expecting a promotion for three years and criticising Wakamotoharu's lack of effort in training. Sōkokurai, for his part, commented that he had had to encourage him since the end of 2018 in order for him to give himself the means for promotion.^[12] During his first jūryō tournament, Wakamotoharu scored only five wins and was demoted back to makushita. He however returned to jūryō after a 6–1 record at makushita 1 in September 2019.^[13]

Since his master (former Ōyutaka) was from Niigata Prefecture, Wakamotoharu regularly attended training camps organized by his stable to scout promising young talent, training notably with future Ōnosato.^[14]

In November 2019 he had to apologize after a picture of him bound to a chair and gagged with tape was posted on social media by fellow wrestler Abi.^[15] The prank was criticized for seeming to make light of past incidents of violence within sumo stables, and the Japan Sumo Association responded by banning sumo wrestlers from having individual social media accounts.^[16]

Makuuchi career

In December 2021 the Japan Sumo Association released the rankings for the January 2022 tournament, and he was promoted to the top makuuchi division, joining his younger brother Wakatakakage.^[17] Wakamotoharu and Wakatakakage are the 12th pair of brothers to both be ranked in the top division at the same time.^[18] He is the second member of Arashio stable to make the top division following Wakatakakage in November 2019, and the first since the current stablemaster, former maegashira Sōkokurai, took over.^[19] Speaking to reporters Wakamotoharu recalled the difficulty of beginning 2021 by having to sit out the January tournament because of a COVID-19 infection but ending it with his best result as a sekitori, an 11-4 record in November, which saw him win promotion.^[4] He said that he hoped he would be able to outdo his younger brother.^[20] At the time of his promotion, the supporters' association in his hometown of Fukushima gave him a replica of the keshō-mawashi worn by his grandfather Wakabayama. On display in his parents' chanko restaurant, the original keshō-mawashi depicts a lion dance scene.^[18]

In the January 2022 tournament Wakamotoharu secured a winning record in his makuuchi debut on Day 14 when he defeated Tobizaru.^[21] His second straight winning record came on Day 12 of the March 2022 tournament, when he defeated Endō to move to 8–4.^[22] He finished the tournament with another 9–6 record.^[23]

Wakamotoharu's bout against Terunofuji in the July 2022 tournament was stopped after two minutes by gyōji Shikimori Inosuke after Wakamotoharu's mawashi became undone. After a pause of about ten minutes for a mono-ii and to reset the positions of the wrestlers, Wakamotoharu was defeated when Terunofuji quickly swung him out of the ring with an underarm throw.^[24]

After two consecutive 10-5 winning records in the top maegashira ranks, Wakamotoharu was promoted to komusubi for the January 2023 tournament. He secured a winning record in his san'yaku debut on the 14th day.^[25] He retained his komusubi ranking in the March banzuke.^[26] In May 2023 he was promoted to sekiwake, making him and his brother Wakatakakage the fourth siblings in history to reach sumo's third-highest rank, and the first since yokozuna brothers Takanohana and Wakanohana in the early 1990s.^[27] During the May tournament, he notably defeated Ōzeki Takakeishō on Day 14.^[28] He finished the tournament with a 10-5 record and was awarded the Technique prize.

After the tournament, the hypothesis of Wakamotoharu's promotion to ōzeki received a response from the chairman of the judging committee, Sadogatake, who commented that the July tournament would be one where promotion to ōzeki would be considered if his results were good enough.^[29] Wakamotoharu would need 12 wins at the July basho to reach the normal ōzeki promotion requirement of 33 wins at san'yaku in three tournaments.^[30] Commenting on his potential promotion, Wakamotoharu expressed his relief at seeing his career finally stabilize in the sport's top division. Similarly, he confided that his position as ōzeki-tori (candidate for the rank of ōzeki) came as a surprise to him, as he has spent the majority of his career trying to catch up with his brother Wakatakakage in the rankings, his younger brother also having been in his potential promotion situation before him. Aware of his situation he also expressed his wish to become the equal of former ōzeki Kaiō and Chiyotaikai.^[31]

Prior to the July tournament, Wakamotoharu received a keshō-mawashi from his Fukushima patronage association. Designed by his mother, who used to work in the design industry after graduating from an art school, the design features flowers and fruit from the prefecture to evoke the Hanamiyama Park.^[32] During the tournament, however, Wakamotoharu lost his chance of the ōzeki title when he suffered his fourth defeat on Day 12 to returning ōzeki Kirishima.^[33]

Wakamotoharu lost his san'yaku status for the first tournament of 2024, having been demoted to the rank of maegashira 1. On Day 2 of the tournament, he claimed his very first kinboshi (gold star) with an upset victory over Yokozuna Terunofuji in a match lasting 1 minute and 42 seconds.^[34] This was followed up the next day with a victory over one of the ōzeki competitors, Takakeishō.^[35] Wakamotoharu finished the tournament with 10 wins, with reports suggesting his record to be enough to earn promotion back to the san'yaku ranks. For his feat in beating the yokozuna and several other san'yaku-ranked opponents, he received the Outstanding Performance Prize.^[36]