Itsuki Nakano is the fifth and youngest of the Nakano quintuplets. She presents as serious, earnest, and exceptionally well-mannered, consistently waking before her sisters and maintaining perfect school attendance and punctuality. Her speech is formal and polite, frequently employing keigo, leading her sister Nino to label her overly straight-laced. Despite this mature demeanor, she struggles with expressing her true feelings openly and holds grudges; she initially rejected Futaro Uesugi's tutoring after their first encounter, where he criticized her eating habits and dismissed her academic request. Her appearance features reddish-orange hair (varying in shade across media) adorned with distinctive star-shaped hairpins near her eyes – accessories Futaro once called unfashionable. An expressive ahoge shifts with her emotions. Like her sisters, she possesses a well-endowed figure and stands 159 cm tall. She wears glasses during studying or tests due to poor eyesight, though documentation is inconsistent on whether she is near-sighted or far-sighted. Academically diligent and precise, she excels in science and ranks among the higher-performing quintuplets. However, she often spends excessive time on exam questions, hindering her efficiency. Despite strong observation and deduction skills, she was the last sister to recognize Miku's affection for Futaro. Notable weaknesses include a notoriously poor sense of direction and susceptibility to fear, particularly regarding ghosts or horror, which can reduce her to tears. A defining passion is her immense appetite and love for food; she is frequently depicted eating or discussing meals. She occasionally prioritizes food over fairness to her sisters, such as scheming to sample all their cakes under the guise of sharing. This culinary interest evolved into a professional aspiration: she adopted the pseudonym "M.A.Y." (referencing May, the fifth month) as a food critic. She later pursued a career in education, aiming to become a teacher like her late mother, Rena, a goal receiving full sisterly support. Her background includes a childhood marked by poverty before her mother's remarriage to Maruo Nakano. Rena's death profoundly impacted her; she visits her mother's grave monthly, striving to honor Rena's resilience. Itsuki shares a close bond with Nino, as both possess long hair, poor eyesight, fear of needles, and morning exercise routines. Her relationship with Futaro evolved from hostility to mutual respect; she addresses him as "Uesugi-kun" and gradually becomes a trusted confidante, offering unintentionally impactful advice. She also formed a sisterly connection with Futaro's younger sister, Raiha. In later story arcs, including post-wedding media, Itsuki pursued her teaching career. She initially struggled with workload management but eventually insisted on overcoming challenges independently, symbolizing growth beyond reliance on her sisters or Futaro. This development culminated in her becoming a science teacher, occasionally assisting at a cram school, and demonstrating increased confidence. Key trivia includes her birthday discrepancy (born May 6 at midnight but celebrating May 5 with her sisters), her Taurus zodiac sign, and her fire-themed attribute in merchandise. She uses polite speech patterns inherited from her mother and maintains daily habits like sit-ups and yoga. Her sisters tease her about her appetite, though she weighs around 50 kg.