Lets Seiba, also known as Retsu Seiba, is a supporting character in the anime Bakusō Kyōdai Let's & Go!! Max. He is the older brother of Go Seiba, and together they were the protagonists of the earlier series. In Max, Lets continues to be an accomplished Mini 4WD racer who has matured through his experiences in national and world competitions. His background includes being a former member of the TRF Victorys, the team that won the World Grand Prix. Following those events, he travelled to America with the team but returned to Japan due to difficulties with the language. Back home, he took on the masked persona of the Masked Fighter, providing commentary and guidance during Mini 4WD races while maintaining a low profile. His personality is calm, patient, and methodical, contrasting with his brother’s impulsive nature. He is a strategic thinker who excels at analysing race conditions and tailoring his cars for cornering and precise handling. His primary motivation is to see Mini 4WD racing enjoyed fairly, and he supports new racers like the Ichimonji brothers in their battles against the aggressive battle-racing philosophy of the Borzoi School. He also has a protective and encouraging relationship with his younger brother Go, and maintains friendly rivalries with other veteran racers. Throughout the Max series, Lets remains a steady, reliable presence, using his deep knowledge of machine tuning and racecraft to help others improve. His notable abilities include exceptional control of his cars through tight turns and his capacity to adapt quickly to different tracks and opponents.