Career
He competed in the singles and doubles events at the 1924 Summer Olympics. In the singles event he had a bye in the first round and lost in the second round to January Koželuh. In the second round they were beaten by the Spanish brothers José Alonso and Manuel Alonso in four sets.
Okamoto participated in the 1924 Wimbledon Championships, playing in the singles and doubles events.
In the singles he lost in the first round in four sets to eventual finalist René Lacoste. In the doubles he teamed up with Khoo Hooi-Hye, reaching the third round in which eventual champions Frank Hunter and Vincent Richards proved too strong.
He became president of the Dai Ichi Trading company and later in life was an adviser to the finance ministry.