Aza Touma is the younger brother and right-hand man of the infamous bandit Aza Choubei. He is a major supporting character of Hell's Paradise: Jigokuraku.

After his brother was arrested, Touma infiltrated the Yamada clan in order to reunite with Choubei in prison and presented him with the shogun's mission to acquire the Elixir of Life from the dangerous island believed to be Shinsenkyou. With the reward being a pardon exempting the criminal of their past crimes, Choubei accepted and was assigned Touma as his Yamada Asaemon monitor.

(Source: Jigokuraku Wiki)