Kikou Sadamune is an uchi gatana, a sword from the late Kamakura period, who appears in Zoku Touken Ranbu: Hanamaru. He is a sword with a long history, notably passed down through the generations of the Tokugawa clan, the shogunal family that ruled Japan for centuries. His name, Kikou, is derived from a distinctive engraving on his tang, a chrysanthemum set within a hexagon that resembles a turtle's shell; this pattern is also the basis for a specific style of decorative rope bondage, which is reflected in the ropes he wears as part of his attire.

Kikou presents a personality that is at once theatrical, intense, and deeply complex. On the surface, he often speaks in a dramatic and flirtatious manner, addressing his master as "my Captain" or "dearest Master" with a tone that can seem teasing or provocative. He frequently makes pointed remarks about being worked hard or even mistreated, asking if he is to be "castigated" or expressing that it is a "lovely thought" to be covered in dirt from fieldwork. This playful yet masochistic demeanor suggests he derives a certain satisfaction from being under the control of a powerful master. However, beneath this veneer lies a sharp, perceptive, and somewhat philosophical individual. In his letters, he contemplates the nature of power and submission, musing that people desire control exerted upon them, as surrendering to a significant authority is preferable to being lost in a "lonesome wilderness". This analysis reveals a keen understanding of human nature and reflects his own experience serving the powerful Tokugawa house.

His primary motivation is centered on his relationship with his master, the Saniwa. He has an unwavering and almost absolute trust in them, explicitly stating, "You have my trust, so do with me as you will. Be as harsh as you wish, I can take it". This "endless master's supremacy" defines his actions and desires, as he seems most fulfilled when serving a master he deems splendid and significant. Within the narrative of the Hanamaru citadel, he acts as one of the swords protecting history, though his role is as much about personal interaction as it is about combat. He forges key relationships with other swords, particularly those with ties to the Tokugawa shogunate, with whom he likely shares a sense of history and common experience. His interactions with the protagonist, the Saniwa, are the most significant, with the relationship evolving from a formal master-servant dynamic to one where he openly entrusts his entire being to their will.

While specific developmental arcs in the anime are subtle, Kikou demonstrates a consistency in his loyalty, though his manner of expressing it matures. He starts by teasingly asking if the master wants to "press my buttons" and ends by stating he has "grown strong" specifically for their sake. This indicates a shift from a performative provocation to a more earnest declaration of his purpose. His primary notable ability is his skill in battle as a capable and robust sword, wielding his blade with precision. Furthermore, his sharp intellect and psychological insight serve as a secondary ability, allowing him to understand motivations and manipulate situations with his words. His entire persona, including his provocative speech and aesthetic, is itself a notable trait that defines his presence in the citadel.