Yamadera Kouichi (山寺 宏一), born June 17, 1961, is a Japanese seiyuu from Shiogama, Miyagi, Japan. His nickname is Yama-chan (山ちゃん) and he was once married to fellow seiyuu Kanai Mika. In Hajime no Ippo he voiced Sanada Kazuki and succeeded the role of Nekota Ginpachi after the passing of Nagai Ichirou.