Born in Japantown, San Francisco to two Issei, a tailor and a midwife from adjoining villages in Oita and Fukuoka Prefectures in Kyushu, Japan.
His instructors included John Haley and Erle Loran, who worked with Hans Hofmann.
In the 1930s, Yamamoto was active in the art scene of the San Francisco Bay area until being incarcerated in May 1942 as part of the mass internment of people of Japanese ancestry during WWII that followed the signing of Executive Order 9066.
He was released early due to the sponsorship of Takashi Ohta, an artist who housed him in his West Village home in New York City.
They then traveled extensively, living at times in different countries, and Yamamoto continually practiced his art.