I belive, in Japan, Koyama Rikiya is more known for serious theater acting than voice acting. The following line from wikipedia should be more than enough to demonstrate his quality as a actor. I don't see, as an actor, you can top receiving good reviews of your performance of a Shakespeare play in England.
Since then, he has appeared in many plays, including "
The Merchant of Venice" staged last October and November. He played the role of Antonio. The play was performed in the
UK, the
Netherlands,
Romania, and Japan and received a favorable reception.
http://en.wikipedia.org/wiki/Rikiya_Koyama
Actually, I found the original review
http://www.newburytheatre.co.uk/archive/200110a.htm