Hosokawa Uichirō was born in Osaka on 25 November 1891, the son of Hosokawa Matsujirō. As a sumo wrestler with the Dewanoumi stable, he was active from January 1910 to January 1923 as Ōnishiki Uichirō. He was the 26th yokozuna in sumo, having attained that title in May 1917. He traveled to Honolulu, Hawaii on 18 June 1921, having left Yokohama on the Taiyo Maru on 9 June.
In January 1923, Uichirō attempted to intervene in the Mikawajima incident in Tokyo, but failed, and left sumo as a result. He entered Waseda University and graduated; he went on to work as a sumo commentator for newspapers. He died on 13 May 1941. His resting place is at Sōji-ji at the Tsurumi ward of Yokohama.
Sources
"Hawaii, Honolulu Passenger Lists, 1900-1953," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QV9Z-DVT4 : 16 March 2018), Uichiro Hosokawa, 1921; citing Ship , NARA microfilm publication A3422 (Washington D.C.: National Archives and Records Administration, n.d.).