Shun Yamaguchi (山口 俊, Yamaguchi Shun, born July 11, 1987) is a Japanese professional baseball pitcher for the Yomiuri Giants of Nippon Professional Baseball (NPB). He previously played for the Yokohama BayStars/Yokohama DeNA BayStars of the Nippon Professional Baseball (NPB), and for the Toronto Blue Jays of Major League Baseball (MLB). He is the first Japanese player to make his MLB debut with the Blue Jays, and also the first MLB player who had never played for any baseball teams in the United States.