According to "Shoku Nihongi" (Chronicles of Japan II), in 761, KOMA no Oyama was designated as Kenbokkaishi (a Japanese envoy to the Bokkai Dynasty) by Emperor Junnin and sent to Bokkai (Balhae) along with Oshinpuku, Bokkaishi (a Korean envoy to Japan).
761年（天平宝字5年）、淳仁天皇から遣渤海使に任じられ、渤海使の王新福を伴い派遣されたという（続日本紀）。