Yoichi Erikawa co-founded Koei with his wife Keiko Erikawa in 1978, initially as a chemical wholesaling company. Erikawa developed video games as a hobby, including the earliest Japanese RPGs, before eventually developing the influential strategy game Nobunaga's Ambition. Due to its success, he converted his company into a game studio, and he and his wife set to work on video games full-time.
Erikawa adopted the pen name of Kou Shibusawa and is commonly credited as such in games he produces. He currently holds the role of general producer at Koei as well as the role of Executive President of Koei Tecmo Holdings.