Mutsu no Kami Yoshiyuki is a sword warrior who embodies the cherished uchigatana of Sakamoto Ryoma, the influential figure of the Bakumatsu period. As a manifest spirit, he retains a rustic, unpretentious appearance that belies a keen mind and a forward-looking perspective. He is defined by his bright, honest, and straightforward nature, openly pursuing his own ambitions while remaining deeply loyal to his master. He believes that swords have become obsolete and therefore chooses to fight with a handgun alongside his blade, reflecting his embrace of innovation and change. His speech is marked by a Tosa dialect and a booming, hearty laugh that reveals his bold and generous character, yet beneath this boisterous exterior lies a gentle soul who does not truly enjoy conflict.

In the narrative of Touken Ranbu Kai Kyoden, which adapts the stage play centered on the Honnoji incident, Mutsu no Kami Yoshiyuki takes part in the pivotal mission to protect history. His role showcases his adaptability and resourcefulness in battle, combining traditional swordsmanship with modern firearms. He maintains a complex dynamic with other sword warriors, particularly those associated with the Shinsengumi, whom he views as figures who failed to move with the times. Through his experiences, he demonstrates a commitment to progress and a desire to shape the future, constantly seeking new knowledge and tactics. His abilities include precise marksmanship with his revolver, agile sword techniques, and a strategic mind that values experimentation and preparation. Over the course of the story, he remains true to his core principles of loyalty and ambition, growing stronger in both skill and resolve as he fights for the dawn of a new era.