An outstanding high school player at Kamloops Secondary and the MVP in their 1990 championship team (a 36-7 victory over Centennial), Yamaoka went on to play at UBC following his secondary school career and was named a 1992 Western Conference All-Star.
At UBC, Yamaoka led the Thunderbirds in rushing in three of his five seasons there and, as of 2019, holds the UBC records for rushing attempts in a season (set in 1992) and career rushing attempts. He went on to play in the CFL for the BC Lions and Winnipeg Blue Bombers from 1997 to 2003. More recently, he coached the Kamloops Broncos of the British Columbia Football Conference until retiring in 2018.
As of 2019, he remains in the sports industry as an interior sales representative for Big Kahuna Sports.