Haruhiro Hamaguchi

Haruhiro Hamaguchi (濵口 遥大)

• Bats Left, Throws Left
• Height 5' 8", Weight 176 lb.
• School Kanagawa University
• High School Miyaki High School

• Born March 16, 1995 in Kiyama, Saga Japan

BR Register page

Biographical Information

Haruhiro Hamaguchi pitched in Nippon Pro Baseball for 8 years.

Hamaguchi played for Japan at the 2014 Haarlem Baseball Week and in the 2015 Universiade, and was on a Japanese collegiate team that faced their U.S. counterparts in a series in the summer of 2016. The Yokohama BayStars picked him in the first round of 2016 NPB draft. Hamaguchi had an excellent rookie season, going 10-6, 3.57 in 22 starts for the team that won the Central League pennant. He did lead the league with 69 walks in 123 2/3 innings, but his 136 strikeouts placed his 5th, just behind teammate Shota Imanaga. He finished third in the voting for the 2017 Central League Rookie of the Year Award (Yota Kyoda was the winner).

Yokohama faced the Softbank Hawks, the perennial power from the rival Pacific League, in the 2017 Japan Series. Softbank won the series, four games to two, but Hamaguchi was one of Yokohama's few heroes: he started Game 4 on November 1st with his team facing elimination and turned in a masterful performance, keeping his powerful opponents hitless for 7 1/3 innings becoming only the fourth pitcher in Japan Series history to turn in such a performance. Daisuke Yamai had famously pitched the first eight innings of a combined perfect game for the Chunichi Dragons on the same day exactly ten years earlier, and Minoru Murayama (in 1962) and Shinji Sasaoka (in 1991) had done the same in earlier series. He left with a 3-0 lead after he giving up a pair of singles in the 8th and relievers Spencer Patton and Yasuaki Yamasaki completed the 6-0 win.

However, Hamaguchi was unable to reproduce the success of his rookie season in following years, going 4-5, 3.90 in 2018. He walked 5 straight batters on Hiroshima Carp to set the NPB record, and he also became the first pitcher in 2-league era to walk 4 consecutive batters when bases were loaded. He was part of the Japanese team that took part in the 2018 Nichi-Bei Series against MLB All-Stars. Hamaguchi then went 6-5 with a 3.17 ERA in 2019, and he was 6-5 with a 4.60 ERA in 2020. He improved to 5-7 with a 3.94 ERA in 2021, and he had a 8-7 record with a 3.36 ERA in 2022. Hamaguchi was 3-7 with a 4.50 ERA in 2023, and he also went 2-2 with a 2.68 ERA for the Cangrejeros de Santurce in winter ball. He was 2-4 with a 3.25 ERA in 2024, and he pitched 13 games with a 6.46 ERA for the Mayos de Navojoa in the winter. The BayStars then traded him to the Softbank Hawks for Masaki Mimori, but he didn't reach the big club in 2025 and he announced his retirement.

Overall, Hamaguchi was 44-46 with a 3.76 ERA, struck out 658 and pitched 703 1/3 innings in 8 seasons in NPB.

Sources

• Wiki Japan