Kurumi Shiratori attends Arisugawa Academy as a first-year student, navigating its strict atmosphere through restless mischief fueled by her affluent upbringing. She stands 151 cm tall, weighs 43 kg, and displays long platinum blonde hair in twin-tails with small bows, frequently accessorized by pink headphones bearing a large white bow. Her outwardly playful demeanor masks surprising maturity, shown through emotional perceptiveness like deciphering Haruna Kasuga's intentions and earnest involvement in serious matters—assisting Saki Izumo with synesthesia colors or voicing concern over local shop closures.

Though deeply grateful to Miyu Sakurada for repeated rescues, Kurumi persists in her pranks, often targeting earnest individuals like Haruna under the guise of "training" her kindness, or teasing Muni Ohnaruto and Rinku Aimoto for their reactions. Miiko Takeshita serves as her primary partner in mischief, their matching height and temperament creating a sisterly dynamic. Childhood ties bind her to Esora Shimizu of Peaky P-key, who occasionally joins schemes or outmaneuvers Kurumi. She also interacts with Noa Fukushima, whose family’s sweets store the Shiratoris patronize, leading Noa to monitor Kurumi per her grandfather’s requests.

Beyond pranks, Kurumi pursues art and Lyrical Lily’s VJ duties with dedication despite academic aversion. She dislikes horror themes and admires Hiiro Yano, addressing her as "Hiiro-senpai." Her narrative includes rivalry with Hiiro in *Petit Mix*, where she strategizes retaliation after falling prey to pranks, and group activities like Lyrical Lily’s snack tastings or horror-concert preparations. Her trickster identity—sometimes dubbed "Tricking Timebomb Kurumi"—consistently coexists with underlying loyalty to friends and community.