Chisato Chikaishi is Kazuya Kagami's childhood friend, knowing him since their early years. They often played together as children, including games like playing house with dolls. When teased by other children, Kazuya stopped playing, but Chisato persisted, holding one doll while Kazuya held the other. This established her pattern of consistently supporting and staying involved in his life, later extending to academic help and frequent lecturing at school. Her personality is studious, prudent, and caring, often showing concern for Kazuya's well-being. However, she reacts violently to extremely unpleasant situations, especially involving perverted behavior. Her harshness toward Kazuya stems from underlying care. She is simple and modest, creating an Amasogi born from a straightforward desire to study with Kazuya at his house; this Amasogi dissipated once he invited her, fulfilling her wish. Physically, Chisato has a plain appearance with thick eyebrows and black hair typically tied in a braid, often worn with glasses. Her look transforms noticeably when she unties her hair and removes her glasses, revealing a more attractive appearance. She initially had bangs but later styles her hair with her forehead exposed, the bangs framing the sides of her face. In a gender-swapped scenario, her face remains unchanged while her hair shortens. As Class Representative of Kamioka East Middle School's Class 2-2, she frequently uses a harisen (paper fan) to discipline slackers, particularly targeting Kazuya or Shirou Shiramine for questionable behavior or neglected responsibilities. This reinforces her Tsundere traits—generally sweet-natured but quick to resort to violence when provoked or frustrated. She possesses no supernatural abilities beyond those of an ordinary human but demonstrates skill in wielding the harisen as a comedic weapon. In the Dream World, she temporarily gains the ability to summon and command her Amasogi after receiving a special charm from Kukuri, an isolated occurrence. Her involvement spans multiple story arcs. She appears during initial Amasogi confrontations in the Introduction Arc, remains active through the Hakusan Shrine Arc, reappears significantly in the Sunao Sumeragi Arc (especially in chapters before Kazuya's dream sequence), and features consistently throughout the Reversal Arc, underscoring her ongoing role in both mundane school life and the supernatural incidents surrounding Kazuya.