A late bloomer, Yamaji joined the Canon Eagles ahead of the 2012 Top League season. For the first four years of his career with the Eagles, he was largely a bit part player making substitute appearances, however in 2016 he finally established himself as a regular in the starting XV.[4]
International
At the age of 31, Yamaji received his first call-up to Japan's senior squad ahead of the 2016 end-of-year rugby union internationals. He debuted as a second-half replacement in Japan's 28–22 victory over Georgia in Tbilisi on 12 November 2016.[1]