The events of the anime series "Kengan Ashura" take place in Edo period Japan. Gladiator fights are gaining popularity in the country, and those who are relatively well-off strive to participate in these spectacular battles. They buy fighters and pit them against each other in the arena, with the winner taking all. In this system, a fighter named Oma Tokita, also known as Ashura, manages to rise to the top by repeatedly defeating his opponents. He catches the attention of a prominent merchant named Hideki Nogi.