Ken Yamaguchi was a Japanese actor, voice actor and narrator. He was represented by OYS Produce. His son, Kiyohiro Yamaguchi, is a fellow voice actor. He was most known for the roles of Ashuraman, The Omegaman, Prisman, Genji Togashi, Flazzard, Black Dragon, and Ein. Yamaguchi died on October 24, 2011, due to acute heart failure.