Masaki Jyonai

Masaki Jyonai (城内 政樹) is a Japanese racing driver and businessman.

Racing career
Jyonai started karting in 1988; he is noted for his extensive experience in kart racing, having won numerous karting championships. He moved to car racing in 1993, racing in the Suzuka 1000 km in the Proto 2 class; he won on his debut.

Jyonai began competing in Super GT in 1997 with the SigmaTec Racing Team. As of 2023, he has won two races; his best finish in the championship is 5th, achieved in his first year in the series. Outside of racing, Jyonai is the CEO and President of Marusho Co. Ltd., a company involved in the lighting, security and construction sectors. He is also a lecturer at the karting classes of Honda Racing School Suzuka as well as a color commentator for various television programs.

He occasionally competes using the pseudonym Guts Jyonai (Guts城内); Jyonai says he took the name from comedian Guts Ishimatsu. In more recent years he has reverted to using his real name.

Complete Super GT results
(key) (Races in bold indicate pole position) (Races in italics indicate fastest lap)
 * Season still in progress.