Asashio Tarō IV (born 9 December 1955 as Suehiro Nagaoka) is a former sumo wrestler from Muroto, Kōchi, Japan. His highest rank was ōzeki. A former amateur champion, he turned professional in 1978. He won one top division tournament championship and was a runner-up on four other occasions. He won fourteen special prizes, including a record ten Outstanding Performance Awards, and five gold stars for defeating yokozuna. He retired in 1989 and became head coach of the Wakamatsu stable, which in 2002 merged with Takasago stable. He stood down as head coach in 2020.