Masui

Masui (written: 増井 or 桝井) is a Japanese surname. Notable people with the surname include:


 * Hirotoshi Masui (増井 浩俊), Japanese baseball player
 * Toshiki Masui (桝井 俊樹), Japanese equestrian
 * Yoshio Masui (増井 禎夫), Japanese biologist