Asashoryu performs the dohyo-iri during a regional tour in 2004.
The number of spots in the top division increases for the first time since January 1991, from 40 to 42. The second highest juryo division increases from 26 to 28.
At the Hatsu basho in Tokyo, achieving his first ever undefeated yusho, YokozunaAsashoryu wins his 5th championship. Runner-up is former sekiwakeKotomitsuki, who has fallen temporarily to a maegashira rank but produces a fine 13–2 score and wins the Fighting Spirit Prize. Kakizoe wins 11 and is rewarded with the Technique Prize and promotion to the sanyaku ranks for the first time. OzekiTochiazuma, who was hoping for yokozuna promotion after winning the previous tournament, can only produce a disappointing 9–6 score. Former komusubiWakanoyama wins the juryo division championship. The makushita championship is won by the 17-year-old Hagiwara (now Kisenosato) with a perfect 7–0 record. Announcing their retirements are former komusubi Oginishiki and two former juryo veterans; the 38-year-old ArgentineHoshitango and the 39-year-old Mutsuhokkai, whose career spanned 23 years.
The Sumo Association hold exhibition tournaments in South Korea, visiting Seoul on the 14th and 15th, and Pusan on the 18th. Former top division wrestler Kasugao is from South Korea and is enthusiastically cheered on by the crowds. Asashoryu wins the exhibitions.
At the Haru basho in Osaka, Asashoryu chalks up a second 15–0 championship in a row to take his 6th overall. His winning streak now stands at 30 matches. The ozeki Kaio and Chiyotaikai both have excellent tournaments and finish runners-up on 13–2. Tochiazuma, by contrast, drops out after only two days. The fourth ozeki Musoyama, who was in danger of demotion, retains his rank with a 9–6 score. Maegashira 12 Asasekiryu is the third runner-up on 13–2 and wins two special prizes for Outstanding Performance and Technique. Former sekiwake Kotonowaka, at the age of nearly 36, wins 11 matches and his fourth Fighting Spirit Prize. MongolianHakuho wins the juryo championship after a playoff with Hayateumi and earns promotion to the top makuuchi division. BulgarianKotoōshū wins the makushita championship with a 7–0 score and is promoted to juryo along with Hagiwara and Toyonoshima.
The Takekuma stable, run by the former sekiwake Kurohimeyama, shuts down. This is because his only wrestler (his son Hagurokuni) is retiring. Takekuma is moving to Tomozuna stable and says he may re-open his stable at some point in the future.
Tochiazuma in 2004, a year in which was twice demoted from the ozeki rank after injury problems.
At the Natsu basho in Tokyo, Asashoryu's winning streak is sensationally halted at 35 by maegashira Hokutoriki, who has never defeated a yokozuna before. Hokutoriki remains in contention for the title right up until the end of the tournament. Coming into Day 15 on 13–1, one win ahead of Asashoryu, he is defeated by Hakuho (who scores 12–3 and wins the Fighting Spirit Prize in his debut top division tournament) and subsequently loses a playoff to Asashoryu, who wins his 3rd championship in a row, and his 7th overall. Hokutoriki is rewarded with the Outstanding Performance and Technique Prizes. Tochiazuma is still unable to compete and loses his ozeki status. Veteran former ozeki Takanonami, who has been fighting in the maegashira ranks for most of the last four years, announces his retirement, leaving the newly renamed Takanohana stable without any sekitori ranked wrestlers. Former komusubi Hamanoshima, in the makushita division for the last two years, and former maegashira Wakanojo, who has fallen all the way to the jonidan division, also retire. Mongolian Tokitenku wins the juryo division championship. Two Estonian wrestlers, Baruto and Kitaoji, make their professional debuts. (Kitaoji quits after only three tournaments.)
At the Nagoya basho, Asashoryu takes his 4th yusho in a row with a 13–2 record. His wins include an extraordinary victory over Kotonowaka on Day 8, in a rematch after he was on the brink of defeat in the first bout. Runners-up are maegashira Miyabiyama and Toyozakura, who each score 12–3. Toyozakura wins the Fighting Spirit Award (no other prizes are given out this time). Kaio scores 11–4. Tochiazuma regains his ozeki rank by winning ten bouts, the fourth man to achieve this after Mienoumi, Takanonami and Musoyama. Hokutoriki, who was promoted to sekiwake after his fine performance in May, manages to win only three matches. Kotooshu wins the juryo championship with a 13–2 score and earns promotion to the top division.
Former juryo wrestler Kanechika takes over the Miyagino stable, replacing the former maegashira Chikubayama, mentor of Hakuho, who stays on as an assistant coach. The new Miyagino Oyakata has no connection to the stable, having wrestled for Kitanoumi stable, but he has been adopted by the widow of a previous head of the stable.
Asashoryu accompanied by Asasekiryu and Kaiho during the September 2004 tournament.
At the Aki basho in Tokyo, Asashoryu's chance for a clean sweep of the 2004 tournaments is dashed when he pulls off a poor 9–6 record and Kaio gets his 5th championship with a 13–2 record. Asashoryu's mediocre performance is attributed to a lack of training due to his wedding reception on 31 August. Tochinonada and Kyokushuzan finish runners-up on 11–4, with Tochinonada receiving the Outstanding Performance Prize, while Roho and Kotonowaka each score ten and share the Fighting Spirit award. Musoyama and Tochiazuma both drop out through injury and will be kadoban in November. Ama wins the juryo championship with an 11–4 score. Tamaasuka wins the makushita title with a perfect 7–0 record and reaches the sekitori ranks for the first time. Hagiwara is promoted to the top division alongside Ama, changing his name to Kisenosato. At 18 years and 3 months he is the second youngest after Takanohana II to achieve this.
At the Kyushu basho, Asashoryu comes back with a 13–2 championship, his 9th overall. Kaio needed 13 wins to gain promotion to yokozuna but after losing to Kotomitsuki on opening day, Hakuho on Day 10 and Miyabiyama on Day 12 can only manage a runner-up score of 12–3 in his hometown tournament, just one win short. Musoyama announces his retirement on Day 3 and Tochiazuma is demoted once again after pulling out on Day 6, leaving Kaio and Chiyotaikai as the only ozeki. Maegashira 1 Hakuho is runner-up alongside Kaio and receives the Outstanding Performance Prize. Sekiwake Wakanosato records an impressive 11–4 and wins the Technique Award. The Fighting Spirit Award goes to Kotooshu who also scores 11 wins in his second makuuchi tournament. Ishide wins the juryo championship. Former maegashira Oikari retires.
29 February: the 42nd Yokozuna Kagamisato, aged 80.