Kōichi Yamadera is a Japanese actor, voice actor, singer and narrator from Shiogama, Miyagi Prefecture. He graduated from Tohoku Gakuin University's economics school and is currently affiliated with Across Entertainment. Before that, he was affiliated with the Tokyo Actor's Consumer's Cooperative Society. His nickname is Yama-chan. As a radio personality, he is known as Bazooka Yamadera among other things.