Koshou is a resident of the Wa Province within the Kingdom of Kei. Orphaned early in life, he took on the responsibility of raising his younger brother, Setki. He is a tall man with dark hair and a large, bear-like physique, which creates an imposing first impression. However, his nature is largely gentle, good-humored, and friendly. He possesses a simple, hearty personality combined with a deep sense of justice.

His primary motivation stems from the suffering he witnesses under the corrupt and oppressive rule of the provincial official Shoukou. Unable to tolerate the hardship inflicted upon his brother and the common people of the province, Koshou becomes the charismatic leader of the Shisui rebels. He rallies the resistance against the governor, driven by a moral imperative to make Wa Province a better place to live, even while privately believing their chance of military victory is slim.

Within the narrative, Koshou's rebellion serves as a catalyst for a major political crisis during the early reign of Queen Youko. The corrupt chief administrator of the kingdom uses the rebellion as a pretext to expand his own power, sending a royal army to crush the insurgents. This situation forces a confrontation that draws the queen herself to the province to understand the truth of the matter. Koshou's actions ultimately force the kingdom to confront the systemic corruption within its own administration.

Koshou's relationships are defined by his fierce loyalty. His bond with his younger brother Setki is a driving force behind his actions, and he is deeply respected by his fellow rebels for his courage and unwavering moral compass. His development in the story represents the vindication of righteous popular resistance. Rather than being a mere insurrectionist to be suppressed, his fight against corruption is recognized as legitimate by the rightful ruler, leading to the fall of the very officials he opposed.

In terms of abilities, Koshou does not rely on magic or supernatural power. His greatest asset is his natural leadership, which allows him to inspire hope and organize a determined resistance among an oppressed population. He is a formidable combatant due to his imposing size and strength, but his defining characteristic is his resilience and the moral conviction he embodies as an ordinary citizen standing against systemic injustice.