Artist for Pocket Monsters SPECIAL (Pokémon Adventures in the English-speaking world) volumes 10 and onward.
His debut was 1993's The Warrior with the Face of a Devil, which ran in Weekly Shounen Sunday. After that, he worked on a number of series for the magazine. The first work of his to be collected in graphic novel format was The Wind of Fight, which was also published in Weekly Shounen Sunday, and ran from 1998 to 2000.
About a year after the end of The Wind of Fight, Yamamoto took over the art for Pocket Monsters SPECIAL after Mato fell ill. His first contributions to the series began in the April 2001 issues of the Shogakukan Gakunen series of magazines. He's been doing the artwork for it ever since.