Kotoha is a member of the Uneme clan, a family whose women possess inherent healing abilities, and she grew up as a childhood friend of the original Arata from the mystical world of Amawakuni. Her background is rooted in service, as the Uneme clan has long served the Hime royal line. When Arata Hinohara from modern Japan switches places with the original Arata, Kotoha remains unaware of the substitution, believing that the Arata she has known since childhood has simply lost his memories after being swallowed by the Kando Forest. This misunderstanding frames her early motivations: she is driven by deep-seated loyalty and a desire to protect and support the person she thinks is her lifelong friend. She accompanies Hinohara on his journey, providing him with Tsukuyo, a Hayagami sword-spirit, and the Michihi no Tama charm, which enables communication between the two Aratas and even with the wounded Princess Kikuri.

Kotoha’s personality is defined by selflessness and quiet resilience. She consistently puts the well-being of others ahead of her own safety, readily enduring physical harm to shield her companions or heal their injuries. Her motivation evolves from a sense of duty and unspoken affection for the original Arata into a more complex emotional bond with Hinohara as she gradually learns his true identity. Initially, she harbored romantic feelings for the original Arata, but those feelings shift toward Hinohara, who reciprocates her affections. Their growing closeness is tested when she discovers the truth about the switch and later when Hinohara, losing control of his increasing power, accidentally harms her. This conflict forces her to reconcile her feelings and her understanding of who he really is.

In the story, Kotoha fills the role of a steadfast companion and a primary healer. She is a magic user who channels the Uneme clan’s hereditary power to treat injuries, making her vital during and after battles. Beyond combat support, she serves as an emotional anchor for Hinohara, encouraging him when he doubts himself and bridging communication between him and the original Arata. Her key relationships center on her childhood bond with the original Arata, which initially motivates her presence, and her deepening connection with Hinohara, which becomes the emotional core of her personal arc. Through these relationships, she develops from a devoted friend who uncritically follows owing to a mistaken belief, into a more aware young woman who freely chooses to stand beside Hinohara despite knowing his true origins and the dangers that surround him. Her notable ability is her Unemezoku healing magic, which she uses with a gentle but determined focus, healing physical wounds and providing a calm presence within the group.