Chiyo Yumehara attends PK Academy, aged 16-17 during the series, with a birthday of June 11 making her a Gemini and blood type B. She stands 158 cm tall, sporting short orange-brown hair usually tied with a pink hairband and honey-colored eyes. She wears the standard female school uniform. Romantic and dreamy by nature, Chiyo experiences frequent infatuations marked by emotional volatility and intense, short-lived pursuits. Despite this instability in romance, she proves perceptive to subtle social cues and remains a loyal friend. Her history is defined by unsuccessful relationships, cementing her reputation for unluckiness in love. Prior to PK Academy, she dated Akanishi Shinichi, who exploited her financially by borrowing money. Later, she dated Shinoda Takeru until his poor hygiene and unpleasant habits caused a breakup. She actively pursued Saiki Kusuo using various tactics, but he consistently rejected her and manipulated events to redirect her interest toward Takeru. After splitting with Takeru, she briefly refocused on Saiki before shifting affections again. A pivotal shift occurred during a school trip to Okinawa. Depressed by classmates' indifference to her swimsuit and ridiculed by strangers at the beach, Kaidou Shun intervened and defended her, resulting in a physical altercation. This act ignited strong feelings for Kaidou within Chiyo. Her attachment triggered significant behavioral changes: extreme weight fluctuations during vacations—gaining weight due to stress and rapidly losing it fearing Kaidou's perception—and mild chuunibyou tendencies like privately calling her hairband a "seal." She maintains a friendship with Kokomi Teruhashi, though an underlying rivalry exists, particularly when both held feelings for Saiki. Chiyo's emotional nature and romantic instability led Aiura Mikoto to predict four divorces in her adulthood. Trivia notes: Her name originates from "Yochi Yume" (予知夢), meaning "Prophetic Dreams." Her aura manifests as tiny hearts, and her guardian spirit is linked to a politician. Academically, she ranks 139th out of 181 students. In junior high, she managed a now-inactive personal website featuring a self-insert novel. Chiyo appears in all official manga chapters, anime seasons, OVAs, and films. Her manga debut is Chapter 5; her anime debut is Season 1 Episode 2. She also features in the video games *The Disastrous Life of Saiki K: Delusion Runaway! Psychic Battle* and *The Disastrous Life of Saiki K: Shijou Psi Dai no Psi Nan!?*.