Ao no Senshi depicts the fate of an atypical boxer. His name is Reggae, he's boxing in lightweight division. His record: 12 wins per knockout for 20 losses by as many knockouts. However, the specialists are impressed by the devastating punch of this mute fighter, which contributes to his myth. But when his path cross the one of a promoter that see in him a crownless king, his life will lead him on the tortuous path to the championship belt.