Chiyo stands as one of the four central protagonists. Outwardly, she embodies an ordinary second-year student at Kashihara Girls' Academy, projecting an image of elegance and normalcy. This facade, however, masks a lethal reality: Chiyo is a deadly ninja. Her true identity as a trained operative clashes dramatically with her schoolgirl persona, forcing her to constantly devise inventive methods to suppress any hint of her ninja skills and maintain her cover.

Her daily existence balances ordinary school routines with friends against the backdrop of chaotic, comedic situations arising from the group's shared secret-keeping. Among her peers is Sekine, a psychic thought-reader aware of Chiyo's hidden nature, complicating their interactions. The central tension between Chiyo's meticulously upheld elegant appearance and her concealed lethal capabilities fuels her role in the group's predicaments, defining her character within this juxtaposition of hidden identity and mundane school life.