Shion Futami is a reserved transfer student who joined the protagonist's class the previous semester. She possesses long, straight gray hair with spiky bangs and a distinctive ahoge, complemented by sharp amber tsurime eyes and a slender, pale frame standing at 157cm tall with measurements of 79-54-80cm. Typically seen in her school uniform of a miniskirt, knee-high socks, uwabaki, and necktie, she also appears in formal shirts, trousers, and occasionally a bikini.

Maintaining a tranquil and distant demeanor often perceived as strange, Shion prefers solitude and immerses herself in books, earning her a reputation as a bookworm who frequently carries literature. Her academic strength lies in language subjects, leading her to join the library committee. Despite her genius intellect, she exhibits social naivety in certain situations and harbors a fear of insects, which sometimes makes her a target for teasing.

A half-orphan with a quarter Scandinavian heritage through her half-Scandinavian mother, Shion gradually opens up emotionally during her school years after encountering the protagonist, whose sincerity helps her connect with classmates. She develops unrequited feelings for him, creating internal conflict as she struggles to reconcile her emotions while respecting his existing relationship with her friend, Yue Imasaka.

Later in life, Shion leaves an overseas job to return to Japan and pursue a career as a novelist. She becomes a regular at the "YuKuRu" cafe, nicknamed "Red Tea Onee-chan" for her preference, and enjoys teatime with friends sharing similar foreign backgrounds, such as Noelle Kagamigawa. Her journey navigates personal growth through meetings and partings, ultimately shaping significant decisions about her emotional life and future path.