Kogarasumaru is a tachi who manifests in the Hanamaru citadel during the second season, Zoku Touken Ranbu: Hanamaru. He is a sword of profound historical significance, unique for its double-edged kissaki moroha design, which represents a transitional form between ancient straight swords and the modern curved tachi. Because of this role in the evolution of Japanese blades, he proclaims himself to be the father of all swords.

This fatherly identity defines his entire personality. Kogarasumaru carries himself with a calm, dignified, and ancient bearing. He speaks with the gentle authority of an elder and possesses a quiet, wry sense of humor. He views every other token danshi as his children, and his primary motivation is to watch over them, offer guidance, and maintain the harmony of the citadel. He is deeply invested in their growth and treats his responsibility as a mentor with sincere care.

Within the story, Kogarasumaru first appears during a cherry blossom viewing party shortly after his arrival at the citadel. His presence serves as a stabilizing and unifying force, particularly during times when newer members struggle to integrate. He naturally bridges gaps between personalities, and his acceptance of his paternal role gives him a respected place in the community. His relationships with the other swords are universally defined by this dynamic, though he tailors his approach to the individual needs of each character.

As a warrior, Kogarasumaru is a formidable fighter. His distinct blade allows for a combat style that blends powerful slashing motions with precise thrusts. He exhibits high speed and durability in battle, making him a reliable asset. Throughout his time at the citadel, his development is marked by a deepening of his role from a symbolic archetype into a genuine, beloved member of the household, forming meaningful bonds that reinforce his commitment to the family he has joined.