Rasuna Sumita serves as an assistant at Kakushi Gotou's manga studio, G-Pro. Her name derives from the Japanese expression "don't drop ink," with Sumita translating to "ink field" and Rasuna blending the characters for "lightweight fabric" and "sand."

Initially joining as a university student, she is attracted by Daikanyama's creative environment rather than personal ambitions to create manga. She takes pride in the recognition her position brings, especially savoring impressed reactions at school reunions when mentioning her job. While outwardly calm and relaxed, she exhibits thoughtful diligence and meticulous attention to detail. She routinely prevents workplace mishaps through proactive actions like data backups, proving reliable in duties despite occasional errors.

Visually, Rasuna possesses wavy, hip-length whitish-gray hair with left-swept bangs and olive green eyes. She typically wears a white shirt with long pink pants, her curvy figure occasionally noted.

Professionally evolving within the manga industry, she rises to become the lead artist for *Manga-Jin* magazine by the time Hime Gotou turns eighteen. She operates her own studio, STUDIO La-Sand, employing two new assistants—fulfilling a common assistant's aspiration despite her original disinterest in becoming a mangaka.

After Kakushi Gotou's accident-induced memory loss, Rasuna supports his recovery by reuniting former colleagues. She participates when Kakushi resumes drawing post-coma with amnesia. During the studio's relocation, a mix-up results in her workspace unintentionally receiving the sign from Kakushi's original studio.

In the anime adaptation, she additionally narrates, explaining manga industry mechanics. Flash-forward segments highlight her unwavering reliability and role as a secret-keeper, honoring her promise to withhold Kakushi's secret from his daughter.