Mongolian Asashoryu put an exclamation point on his second straight Emperor's Cup on Sunday, shoving out Musoyama to improve to 14-1 on the final day of the New Year Grand Sumo Tournament.
Asashoryu, who won November's Kyushu tourney, captured his second title in a row Saturday with a convincing win over Kotomitsuki.
On Sunday, he showed no signs of letting up when he spun Musoyama around after the face-off at Ryogoku Kokugikan and then shoved the ozeki out to his seventh loss.
With the title secured, ozeki Asashoryu assured himself of promotion to grand champion, said Kitanoumi, head of the Japan Sumo Association.
His promotion to yokozuna will result in two foreign-born wrestlers occupying sumo's highest rank.
Hawaiian grand champion Musashimaru, who holds Japanese citizenship, sat out the New Year tourney with an injured wrist.
Many of the sport's top wrestlers, including ozekis Chiyotaikai, Kaio and Tochiazuma, sat out the New Year tourney due to injury.
Grand champion Takanohana retired on Monday.
In other major bouts, No. 3 maegashira Dejima jettisoned seventh-ranked maegashira Wakanosato, giving both wrestlers a record of 11 wins and four losses.
In a battle of sekiwake wrestlers, Kotomitsuki hammered Takanowaka into the dirt surface to pick up his ninth win. Takanowaka, who dropped to 9-6, had to be carted off the raised ring after a cut opened over his left eye.