Haruhiro Hamaguchi (濵口 遥大, Hamaguchi Haruhiro, born March 16, 1995) is a professional Japanese baseball player. He plays pitcher for the Yokohama DeNA BayStars.
In Game 4 of the 2017 Japan Series, with DeNA facing elimination, Hamaguchi did not allow a hit for 7+1⁄3 innings.
On October 10, 2018, he was selected Japan national baseball team at the 2018 MLB Japan All-Star Series.
