Koshi Inaba (稲葉浩志, Inaba Koshi, born on September 23, 1964 in Tsuyama, Okayama Prefecture) is a Japanese vocalist. He graduated from the Department of Education at the prestigious Yokohama National University. He has a degree in mathematics. He and guitarist 松本孝弘 (Tak Matsmoto) form the legendary Japanese rock band, B'z, also featuring drummer Shane Gaalaas and members of DOA. Their debut was in 1988, and he also started his solo career in 1997 with "Magma".