SK8 the Infinity

Original title: SK∞ エスケーエイト

"S" is a dangerous, top secret, no-holds-barred downhill skateboarding race down an abandoned mine. When avid skateboarder Reki takes Langa to the mountain where "S" is held, Langa, who's never been on a skateboard in his life, finds himself sucked into the world of "S", and…?!