is a Japanese racing driver who last competed for TF Sport in the LMGT3 class of the European Le Mans Series.
Koizumi made his car-racing debut in 2004, racing in the Honda Integra Kanto Series, where he took a best result of second in the second round. The following year, he switched to Super Taikyu, racing in the ST-3 class for Tomei Sports alongside Akira Yoshitomi. Finishing sixth in class on debut at Sendai, Koizumi took his best result of the season at the following round at Suzuka despite incurring a ten-second penalty. Having completed four of the eight races in the Super Taikyu schedule, Koizumi and Tomei Sports finished 11th in the ST-3 standings. During 2005, Koizumi also raced in the Suzuka 1000 km for Gaikoku-ya Advan Porsche in the GT300 class. On his GT300 debut, Koizumi finished third in class and sixth overall.
After racing in Formula Toyota in 2006, Koizumi returned to GT300 competition in 2007 by joining Team Gaikokuya in Super GT. Koizumi competed in Super GT on a near-full-time basis until 2011, during which he scored a best result of seventh at the 2010 Pokka GT Summer Special. After concentrating on Japanese Formula 3, Koizumi returned to Super GT in 2015, joining apr alongside Yuki Iwasaki. Completing his first full season in Super GT competition with apr, Koizumi took two 13th-place results as best finishes across the eight-race season in both the season-opener at Okayama and Suzuka.
Returning to single-seaters in 2009, Koizumi joined CMS Motor Sports Project in the National class of the Japanese Formula 3 Championship. Following two seasons with CMS, Koizumi switched to Hanashima Racing, with whom he'd clinch the National class title in 2014 after winning eight of the 15 races. During his five-year tenure in F3, Koizumi also won the 2013 3 Hours of Fuji as he made a one-off appearance in the LMP2 class of the Asian Le Mans Series for KCMG.
Following a seven-year hiatus, Koizumi returned to racing in 2022, joinning ABSSA Motorsport in GT World Challenge Asia alongside Keita Sawa. Taking a best result of fourth in race one at the season-ending Okayama round, the pair ended the season 12th overall and eighth in the Pro-Am standings. At the end of 2022, Koizumi joined AF Corse to make his debut at the final round of the Michelin Le Mans Cup in the GT3 class alongside Kei Cozzolino. The duo started third and held off Jan Magnussen in the closing stages to win on debut.
Returning to AF Corse for 2023, Koizumi raced in the Michelin Le Mans Cup on a full-time basis, alongside Kei Cozzolino marking his first season outside of Japan. The pair finished third in the season-opening round at Barcelona, before winning the penultimate round of the season in Aragón and finishing runner-up in the standings to Racing Spirit of Léman. During 2023, Koizumi also made his WEC debut, racing in at the penultimate round of the season at Fuji alongside Simon Mann and Kei Cozzolino. Qualifying fifth but later getting his time deleted on debut, Koizumi finished his first WEC race in 12th.
In 2024, Koizumi joined TF Sport to make his full-time WEC debut in the LMGT3 class alongside Daniel Juncadella and Sébastien Baud. At Losail, Koizumi qualified 11th, and despite a drive-through penalty for Juncadella for violating track limits later in the race, was able to finish tenth to take his first points in the series. At the penultimate round of the season at Fuji, Koizumi advanced to hyperpole and qualified seventh in LMGT3. In the race, Koizumi ran sixth before his race was ended after his car didn't start following a pit stop. In the final race of the season in Bahrain, Koizumi took his maiden WEC podium by finishing third, which helped him finish 14th in the driver's standings.
Koizumi remained with TF Sport for 2025, albeit switching to the European Le Mans Series, alongside Rui Andrade and Charlie Eastwood. In their first season together, the trio won at Imola and Algarve, as well as standing on the podium at Silverstone, en route to the LMGT3 title at season's end.
â¡ Team standings
() (Races in bold indicate pole position) (Races in italics indicate fastest lap)
() (Races in bold indicate pole position) (Races in italics indicate fastest lap)
() (Races in bold indicate pole position) (Races in italics indicate fastest lap)
<sup>*</sup> Season still in progress.
() (Races in bold indicate pole position) (Races in italics indicate fastest lap)
() (Races in bold indicate pole position; results in italics indicate fastest lap)
() (Races in bold indicate pole position; races in italics indicate fastest lap)
() (Races in bold indicate pole position; results in italics indicate fastest lap)
<sup>*</sup> Season still in progress.