Nino grew up alongside her sisters under the care of their biological father and later their stepfather, Maruo Nakano. From a young age, she took on the responsibility of cooking for her siblings, strengthening her role as the maternal figure of the quintuplets.

Despite her strong exterior, Nino struggles with feelings of abandonment, particularly regarding their biological father, who left them when they were young. This deep-seated fear of loss manifests in her controlling and stubborn nature, especially when it comes to her family and personal relationships.

Initially, she resents Futaro and views him as an intruder, but over time, she develops strong romantic feelings for him, leading to one of the most compelling character transformations in the series.

Nino has long, dark purple hair with straight bangs and twin butterfly-shaped ribbons that she wears on both sides of her head. She has deep purple eyes, complementing her striking and bold personality.

Among her quintuplet sisters, Nino’s fashion sense is the most stylish and trendy. She frequently wears fashionable and feminine outfits, often seen in dresses, skirts, and stylish casual wear. Her school uniform consists of the standard Sakuragaoka High uniform, but she occasionally modifies it to suit her own fashion-forward style.

Nino is headstrong, confident, and unfiltered, often speaking her mind without hesitation. She is blunt and direct, showing little patience for people she dislikes. She frequently clashes with Futaro, viewing him as an intruder in their lives and resisting his tutoring at every turn.

However, underneath her tough exterior, Nino is deeply caring and affectionate. She values her family above all else, often acting as the protector of her sisters. Her insecurities and fear of abandonment drive many of her initial negative behaviors, but as the series progresses, she matures significantly, becoming more open, emotionally honest, and introspective.

Nino is also extremely passionate, particularly in matters of love. Once she falls for Futaro, she boldly confesses her feelings, making her one of the most determined and proactive characters in the series when it comes to romance.

• Early Conflict with Futaro
  At the beginning of the series, Nino is the most hostile toward Futaro, actively trying to drive him away. She is resistant to his tutoring and views him as a nuisance, going as far as to drug him to prevent him from staying with them. Her initial antagonism toward Futaro stems from her fear of change, as she struggles with the idea of an outsider influencing their close-knit family dynamic.

• Transformation and Love Confession
  As time passes, Nino gradually warms up to Futaro, recognizing his sincere efforts to support her sisters. She undergoes a major turning point when she cuts her hair short, symbolizing her desire for change and self-growth. Realizing her genuine love for Futaro, she becomes bold and relentless in her pursuit, openly confessing her feelings and competing with her sisters for his affections. This newfound confidence shifts the dynamic of the series, as she evolves from an initial antagonist to a determined romantic rival.

• Overcoming Personal Struggles
  Throughout the series, Nino reconciles her insecurities, particularly her fear of abandonment. She learns to trust others, accept change, and embrace personal growth, making her one of the most developed characters in the story. Her relationship with Futaro becomes a key emotional thread, as she matures from someone who pushed him away to one of his strongest supporters.