Kogoro Katsura is a samurai from the Choshu domain and one of the main protagonists. He has medium-length dark hair and wears square lower-rimmed black glasses, typically dressed in a teal jacket with olive sections over a red undershirt. His personality is extremely serious, level-headed, and gallant. He often acts as the straight man to his more impulsive partner, Takasugi Shinsaku. Katsura is motivated by a strong sense of duty to protect his nation. He joins Takasugi on a mission to retrieve a mysterious timepiece that can manipulate time, initially seeking to destroy it. After the artifact is stolen, they pursue it to Kyoto and discover an alternate reality where the government has been overthrown by the deity Susanoo. Determined to restore order, Katsura resolves to restart time and save his country. In the story, he serves as a key protagonist and the more cautious counterpart to Takasugi. His most significant relationship is with Takasugi, his trusted comrade from Choshu, and he also interacts with other historical figures in this altered world. While his serious demeanor remains steady, he shows growth in his commitment to overcoming the challenges of a changed era and the consequences of time travel. As a samurai, he is a capable fighter, but his most notable strengths are his sharp intellect, calm judgment, and unwavering composure in crisis.