Yajirou Kojima is a skilled swordsman known as the "Rearguard Tiger," fighting for world unity. Once a rebel, he worked as a mercenary before meeting Rushuna. Despite his disdain for firearms, Yajirou can parry bullets and slice cannon shells with his sword. He dislikes guns because he believes they reduce the value of life to the effort required to pull the trigger. However, he sees Rushuna differently from other gunners. The journey he takes with Rushuna and Mikan to Tento's capital by crossing Mt. Charanbo and White Wizard Lake retraces his path from a failed rebel invasion a year and a half ago, making it emotionally significant for him. Rushuna calls him "Yatchan," a nickname that initially irritates him but eventually grows on him. He has feelings for Rushuna.
In the manga, Yajirou belonged to a branch family of the Kojima clan, led by Midare Kojima and his sister Suguna. Determined to make a name for himself and protect his village, Yajirou set out on a journey. During this journey, Suguna sacrificed her life to save his.
