Koma Sakuraba is a high school student and the childhood friend and classmate of Koito Koganei, the human protagonist of the series. She is characterized by her cheerful and energetic disposition, often speaking her mind without reservation. Koma is highly intelligent; she has demonstrated the ability to remember lesson content simply by listening in class. Her appearance features medium-length red hair and orange eyes, and she typically wears her school uniform.

In the story, Koma serves as Koito's closest confidante and a source of everyday normalcy amidst the supernatural happenings at the Takamimi Shrine. She is always ready to support and cheer up Koito, though she does not hesitate to tease her friend about her devotion to the shrine's elf deity, Elda. Beyond her friendship with Koito, Koma also develops a rapport with Elda, bonding over their shared interest in collecting toys and helping the elf obtain a sought-after item by revealing a local shop that sells vintage toys. This demonstrates her resourcefulness and practical knowledge of her neighborhood.

Koma's motivations are rooted in her loyalty to Koito and her curiosity about the elf and the shrine. She participates in Koito's activities without becoming directly involved in the shrine's rituals or the elves' world. While her character does not undergo a dramatic transformation, she becomes more integrated into the lives of Koito and Elda, acting as a supportive friend who helps bridge the gap between the shrine and the outside world. Her notable abilities include her sharp memory and academic talent, as well as her social skill of connecting with others, even a reclusive elf.