Naoko Kamikishiro is a third-year student at Shinyo Academy in the city where the events of Boogiepop and Others take place. She is a cheerful and bright young woman with a friendly and approachable demeanor that puts others at ease. She has shoulder-length, wavy light brown hair and brown eyes, and is often seen wearing the standard Shinyo Academy uniform. Despite her happy-go-lucky nature, she is known to frequently hum or sing a song titled Life Is Brief, which hints at a more contemplative side to her personality.

Naoko is deeply compassionate and empathetic, always ready to help others and try to understand how they feel. This innate kindness becomes the driving force of her role in the story. By chance, she encounters a being named Echoes, who has collapsed in the street. Echoes is an alien entity sent to evaluate humanity, but he appears as a ragged, speechless man. Moved by his plight, Naoko takes him in and, through a telepathic link that forms between them, learns about his purpose and the threat posed by another creature known as Manticore. Her ability to show compassion to a being that cannot communicate through normal speech is a pivotal moment in the narrative; it is suggested that her kindness ultimately allows Echoes to see the worth in humanity, thereby saving the human race from judgment.

Naoko is close friends with Nagi Kirima, a more stoic and determined girl who investigates the strange occurrences in the city. She also shares a romantic relationship with both Shirou Tanaka and Akio Kimura, maintaining a bond with each of them. Her conversations with Akio reveal a thoughtful and philosophical side, as she once asked him whether he believed human existence was justified and told him about her meeting with Echoes.

Naoko becomes a victim of Manticore, who kills her when she inadvertently stumbles upon the creature during a confrontation. Her death sends ripples through the lives of those who knew her: Akio Kimura receives a letter about her death and returns to investigate, Shirou Tanaka seeks answers about her disappearance, and Nagi Kirima is deeply affected by the loss of her friend. Even after her death, Naoko continues to influence events. In one account, during a later final battle between Nagi Kirima and the entity known as Walpurgis, Naoko appears before Nagi one last time to share final words that help decide the outcome of the conflict.

Her notable abilities are not combat-oriented but rather empathic and telepathic in nature. She possesses a gift for understanding others on a deep level, even beings without language, and she shares a telepathic link with Echoes. This gift, combined with her gentle heart and openness, allows her to connect with a being from beyond Earth and become a key figure in preserving humanity's future.