Retsu is one of two main characters in the series. He's a fifth-grade student who's 11 years old and Go's older brother. Despite being able to control his temper better than Go, he occasionally lets out his frustration with someone. His signature item is a green hat. Red is Retsu's primary color, which matches the color of his hair, eyes, gloves, shirt, and Mini 4WD cars. Alongside Go, they are known as "Lets Go Brothers" (レッツゴー兄弟 Rettsu Gō Kyoudai). In WGP, Retsu is the captain of TRF Victorys team.