Ken'ichirou Sumi is a former Japanese voice actor and actor from Tokyo, born on December 8, 1976. His career included affiliations with the talent management firms B-Box and AIR AGENCY before he transitioned to freelance work. Sumi is primarily known for his role as Fumiki Mizutani, the left fielder for the Nishiura High School baseball team, in the 2007 anime series Big Windup! and its 2010 sequel, Big Windup! ~Summer Tournament Edition~. He also provided the voice for the character Kohei Kuriyama in the 2011 anime Gattai Robot Atranjer. Following his work in voice acting and stage performance, Sumi retired from the entertainment industry. He subsequently obtained a national certification in judo therapy and became the owner of a relaxation salon, though he has suggested the possibility of returning to acting if his business becomes established.