Reki Kyan, a high school student deeply devoted to skateboarding, stumbles upon the underground skate race known as "S" held in a perilous mine after dark. Following a devastating defeat that shatters his board and injures his arm, Reki finds himself unable to skate. It is amidst this setback that he crosses paths with his classmate, Langa Hasegawa, a biracial newcomer with no skateboarding background and a pressing need for cash. When they are coerced by Reki's employer to venture back to "S," they become entangled in a risky wager that pushes Langa onto the racetrack. Little does Reki know, Langa harbors a secret advantage that could turn the tide of the race in a most unexpected fashion.