Keirin is a “world of battle” where physiques clash against physiques, courage clashes against courage. A high school student has taken his first step into the world of track racers, with bicycles as sharp as finely honed swords! He is Kobayashi Morio, a regular customer of Aoba Bicycle Shop, famous for its chromoly horizontal frame bikes! A boy who is just good at riding bikes around town enters the world of competition! Morio stands on the 400-meter track!! A whirlwind special spinoff extra episode of *Aoba Bicycle Shop*, the *Keirin Challenge Arc*!