Ichika Nakano is the eldest of the Nakano quintuplets, born first among her sisters. She assumes a responsible, motherly role within the family, often acting as their leader due to her calm and composed demeanor. This outward maturity masks her internal insecurities and sensitivity, particularly regarding her own perceived shortcomings and her relationships with her sisters. Her appearance features short, light pink hair with a distinctive long strand on the right side, dark blue eyes, and a single earring symbolizing her status as the firstborn. She possesses an average height and a well-endowed figure, often noted for her fashion sense which includes wearing her school uniform with an unbuttoned top or a jacket tied at her waist.

Academically, Ichika initially displays pessimism about her and her sisters' learning capabilities, becoming an early obstacle to their tutor, Futaro Uesugi. Inspired by his dedication, she commits to her studies, balancing schoolwork with her burgeoning acting career. She often studies during breaks on film sets or late at night, demonstrating a strong work ethic. Mathematics is her strongest subject, placing her in the middle academically among the quintuplets. Her career as an actress and model begins in secret, driven by pride as the eldest sister; she intends to achieve success before revealing it to her family. This ambition sometimes strains her relationships, especially when she prioritizes work over family commitments. Her acting skills are exceptional, allowing her to convincingly impersonate her sisters' mannerisms and expressions, though not as flawlessly as Miku. Futaro notes her ability to "see through people," reflecting her sharp insight into human psychology, such as deducing conflicts between others or accurately assessing emotional states.

Ichika's character development is marked by evolving relationships and personal conflicts. Early on, she interacts with Futaro in a teasing, provocative manner, but this gradually shifts to genuine romantic feelings. Her internal struggle intensifies as her sisters also develop affections for him, leading to moments of rivalry. During a significant confrontation in Kyoto, she competes aggressively for Futaro's attention, creating friction with her sisters. This culminates in a pivotal moment where she acknowledges her selfish actions but ultimately reconciles with them, reaffirming her commitment to family unity. Her romantic feelings are further complicated by her role as the eldest; she confesses to Yotsuba her desire to maintain the status quo while simultaneously not wanting "anyone else to have" Futaro, highlighting her internal conflict between selflessness and longing.

In later story arcs, including the honeymoon special *The Quintessential Quintuplets＊*, Ichika faces professional challenges such as the physical demands of acting roles. She initially relies on her sisters and Futaro for support but eventually chooses to tackle these obstacles independently, symbolizing her growth into self-reliance. This decision reflects her broader arc from dependency on familial bonds to embracing individual agency. Her personal habits include being a heavy sleeper who often naps nude or semi-nude, and she maintains a notoriously messy and disorganized bedroom, contrasting her otherwise put-together image.

Throughout the series, Ichika's relationships with her sisters remain central. She acts as a mediator during their disputes, exemplified when she advises Futaro on resolving issues with Itsuki or urges Miku to avoid future regrets regarding Futaro. Despite periods of rivalry, she consistently reaffirms their sisterly bond, emphasizing that family transcends romantic competition. Her dynamic with Futaro evolves from superficial teasing to deep mutual respect, with her providing him emotional support during his struggles while gradually acknowledging her own vulnerabilities to him.