He began his study of Karate at age 6, eventually expanding his study to include Judo and Kendo. As a teen he began studying Yamanni Ryu (or Yamanni-Chinen ryu) with Chogi Kishaba, the direct student of Masami Chinen who was the only instructor of the style remaining in Okinawa. Shihan Oshiro is currently 9th Dan in both Shorin-ryu and 8th Dan in Yamanni ryu.
In 1985 he and Kishaba Sensei founded the RBKD (Ryukyu Bujutsu Kenkyu Doyukai), an organization dedicated to the research and development of Okinawan Martial Arts. He currently teaches in his San Mateo dojo, and holds seminars nationally and internationally.