Yajirou Kojima is a swordsman also known as the "Rearguard Tiger," who battles in an attempt to bring about world unity. A former rebel, he was working as a mercenary until he met Rushuna. Although Yajirou disdains the use of firearms, he is skilled enough to parry bullets with his sword as well as slice massive cannon shells in two. Yajirou hates guns because he believes that gunners see the weight of a person's life in how hard it is to pull the trigger. However he later states that he does not see Rushuna in the same light as he does other gunners. The route that he, Rushuna, and Mikan take towards Tento's capital by crossing Mt. Charanbo and then White Wizard Lake retraces the same route that he followed when he was with the rebel army that attempted to invade the capital a year and a half ago and is thus memory-laden for him. Rushuna calls him "Yatchan", an informal name he is initially irritated with, but grows to accept. He loves Rushuna.

In the manga, he belonged to a branch family of the Kojima clan, This clan was led by Midare Kojima and his sister, Suguna. Yajirou intended to go out and make a name for himself, ensuring the safety of his village. While on a journey, Suguna gave her life to save Yajirou's own.

(Source: Wikipedia)