Fumiyo Fujiyoshi is a student from the third-year class at the fictional Shiroiwa Junior High School, making her fifteen years old at the time of the events she appears in. She is designated as female student number eighteen in the class roster.

Before the program, Fumiyo served as the school nurse's aide, a role that involved helping care for classmates who fell ill during the school day. In the novel and manga adaptations, she is depicted as a quiet and caring girl who is part of Yukie Utsumi's circle of friends. Her personality contrasts somewhat with the film version, where a flashback sequence shows her participating in bullying Noriko Nakagawa by locking her in a school bathroom and writing insults against her, though the significance of this behavior is presented as part of the class's generally hostile environment toward Noriko. In the manga, Fumiyo is seemingly unaware that her classmate Yutaka Seto harbors romantic feelings for her, and he observes that she always looked pretty no matter what she was doing.

Fumiyo's role in the story is tragically brief, as she does not participate in the deadly game itself. While the students receive their instructions in the classroom at the start of the program, she is caught whispering to another student, Yukie Utsumi. The teacher, whose name varies by adaptation as Kinpatsu Sakamochi in the novel, Yonemi Kamon in the manga, or Kitano in the film, throws a knife at her which strikes her directly in the forehead, killing her almost instantly. In the film, Fumiyo is the second student caught whispering, and the teacher uses the same knife later to stab Yoshitoki Kuninobu. After her death, Shuya Nanahara takes a moment to close her eyes, though he cannot bring himself to remove the knife from her forehead, a moment for which he feels immediate regret.

Despite her early death, Fumiyo's death serves as a significant motivating factor for other characters. Yutaka Seto is deeply affected by her death, feeling both grief and anger at himself for being unable to save her. This emotional response leads him to join Shinji Mimura in planning an act of revenge against their captors, and the bomb they construct together is named Fumiyo's Revenge in her honor. Throughout all adaptations, Fumiyo is terrified and bewildered by the unfolding situation like her classmates, but she never has the opportunity to ask questions or understand what is happening before her death. Her blood type is recorded as B.