Noted for simultaneously being a Dominican friar and Zen Buddhist master, Oshida was known for engaging in interfaith dialogue throughout his life.

[3] In 1942, Oshida graduated from Dai-ichi Kotō Gakkō (第一高等学校), a two-year preparatory college that was dissolved after World War II.

After World War II, he attended the University of Tokyo, where he studied philosophy and graduated in 1951.

[3] He enrolled at the Dominican Theological Seminary in Ottawa, Canada in 1958 and was ordained a priest on 8 April 1961.

Among his travels, Oshida visited Thailand, India, Bangladesh, Vietnam, Hong Kong, Taiwan, South Korea, Philippines, Saipan, Poland, Lebanon, Israel, Canada, and the United States.