Harumafuji posted a morale-boosting third victory on Thursday to move back into the winning column at the Autumn Grand Sumo Tournament.
Fellow Mongolian yokozuna Hakuho also won on the fifth day of action at Ryogoku Kokugikan and shares the lead at 5-0 with rank-and-filer Yoshikaze.
Kotooshu was the only major upset of the day and the Bulgarian ozeki dropped into a group of eight wrestlers at 4-1 at the 15-day basho.