Hideo Koma joined JWA in 1961/06 and had his debut match few months later. Besides his real name, the ring names earlier in his career also included "Atsuhide Koma" and "Kakutaro Koma". He became the first attendant for Giant Baba during this time, and the mutual respect between them would stay strong until Koma's death.
In 1970/01, he was sent to Mexico, where he started using the name "Masio Koma", and defeated the legenadry El Solitario on 1970/08/28 to win the World Middleweight Title. Afterwards, he moved on to the United States and wrestled in the Gulf Coast area and then in the Amarillo territory, which would lead to the strong relationship between the Funk family and Baba.
As a matter of course, he was brought back to Japan by Baba when All Japan Pro-Wrestling was established in 1972. Along with Joe Higuchi, Koma would be responsible for booking the foreign talents as well as coaching the rookies. Meanwhile, Kotetsu Yamamoto, who was Koma's respected rival during the JWA days, was the head coach of New Japan Dojo, and although two groups isolated themselves from each other, the friendship between Koma and Yamamoto remained tight, and they would often exchange the idea on coaching of the younger wrestlers.
On 1976/03/10, Koma passed away due to liver failure at the young age of 35.