As a Nisei (2nd generation Japanese-American), Hamanaka was interned in Jerome, Arkansas during World War II due to Executive Order 9066,[1] where he worked on camp newspapers.

Following tours of Teahouse of the August Moon and Auntie Mame, Yama made his first appearance on Broadway in the original production of Rodgers and Hammerstein musical Flower Drum Song as Dr. Li, and understudying Keye Luke in the character of Wang Chi Yang.

Off-Broadway, Yama originated roles in "Santa Anita '42" at both Playwrights Horizons and the Chelsea Theater, and in Frank Chin's The Year of the Dragon at The American Place Theatre.

In the made-for-TV version of Year of the Dragon, broadcast by PBS as part of the series Great Performances in 1975, Yama returned as Pa Eng, the father of the protagonist, played by George Takei, who replaced Randall Duk Kim in the leading role.

The New York Times review stated, "In the best scene of all, as the story moves into Chinese headquarters, Mr. Peck has an ideological Ping-Pong match, swatting it out verbally over a table with an incisive actor named Conrad Yama".

Yama's other onscreen acting included a number of small and supporting roles in film, television, and made for TV movies.

[7] Yama's last onscreen role was a small part in "See China and Die", a made-for-TV movie starring Esther Rolle in 1981.

Several years after his death, a picture of Yama (among other photographs) appeared on the cover of an academically published monograph collecting various profiles of Japanese Americans which has originally been featured in the Nichi Bei Times.