Otoha appears as a young girl but exists solely as a spirit perceptible only to Takuma Hirose. She possesses distinctive white, straight shoulder-length hair styled in a blunt bob with bangs and green, tareme-shaped eyes, complemented by a pale complexion and a slim physique standing 136 cm tall. Her typical attire includes a school uniform featuring a pleated skirt, vest, puffy sleeves, and a ribbon headband or beret, often worn with loafers and pantyhose; sundresses also form part of her wardrobe. Her origin lies as the spirit of Hinata Kagura, Hotaru Kagura's elder sister, who drowned in a river. Her family concealed her death by presenting Hotaru as Hinata. She adopted the name "Otoha" from a character in Hotaru's picture book, representing the "Spirit of the Sounds of Time" (時ノ音の精霊), a figure resolving village conflicts – a role defining her narrative purpose. Otoha displays a consistently cheerful and energetic personality, frequently appearing unexpectedly to cling to Takuma. She uses the masculine pronoun "boku" for herself and designates Takuma as the "Promised Person" (約束の人). Her interactions involve aiding Takuma, though her occasional overenthusiasm misguides him into perilous situations like wild animal encounters. She manifests primarily when Takuma is alone and vanishes upon others' approach. Her abilities encompass communicating with animals and temporarily restoring Takuma's psychosomatic blindness, though she rarely employs her powers otherwise. As the Spirit of the Sounds of Time, she guides Takuma to confront and resolve the village's deep-seated animosity, viewing him as instrumental in fulfilling the picture book's prophecy of peace. Her narrative arc reveals the truth behind the village's strife and Takuma's past. She shows Takuma an illusory world where they are engaged, confessing her love while acknowledging they do not belong together. This culminates in an elaborate illusion (depicted as a "Magical Girl" scenario) based on Hotaru's picture book, serving as her farewell gesture. Before vanishing permanently, she helps Takuma reconcile the village's conflicts and his trauma. Otoha's existence resolves upon the revelation of her identity as the deceased Hinata and the village's acceptance of its buried secrets. Her actions directly facilitate Takuma's emotional healing and the cessation of persecution against Hayami Kohinata, fulfilling the role envisioned in Hotaru's book.