Miku Nakano is the third of the Nakano quintuplets, the five identical sisters at the center of the story. She is introduced as a quiet, shy, and introverted girl who often keeps to herself, frequently wearing a pair of blue headphones around her neck as a sort of barrier between herself and the world. Her reserved nature makes her appear distant or difficult to read, but she is deeply thoughtful and observant. Miku struggles with low self-confidence and a tendency to underestimate herself, often feeling overshadowed by her more outgoing sisters.

Her primary motivation throughout the story is her desire for self-improvement and to become someone worthy of recognition, particularly in the eyes of her tutor, Fuutarou Uesugi. Miku is the first of the quintuplets to develop romantic feelings for Fuutarou, and this becomes a powerful catalyst for her personal growth. She sets personal goals, such as achieving the highest exam scores among her sisters, to prove to herself and to him that she is capable. Her love is quiet but determined, and she works hard to overcome her insecurities.

In the narrative, Miku serves as a character whose journey is centered on building confidence and finding her own voice. She starts off as the most passive of the sisters but gradually becomes more assertive and willing to express her feelings, even confronting her siblings or Fuutarou directly when necessary. Her role also highlights the theme of individuality within a set of identical quintuplets, as she strives to stand out and be recognized as her own person.

Key relationships include her bond with Fuutarou, who encourages her studies and respects her interests, particularly her passion for history. Miku is exceptionally knowledgeable about Japanese history, especially the Sengoku period, and her favorite historical figure is Takeda Shingen. She also has complex relationships with her sisters, especially Ichika and Nino, as they become rivals for Fuutarou’s affection. Despite conflicts, Miku remains loyal to her family and eventually supports her sisters' happiness, even when Fuutarou chooses another.

Miku undergoes significant character development. She learns to cook, becomes more sociable, and gains the courage to take initiative in both academics and romance. She experiences setbacks, such as failed attempts to confess and moments of jealousy, but she does not give up. Her growth is marked by a transition from a self-doubting girl to a more confident young woman who can openly express her desires.

Notable abilities include her academic strength, particularly in social studies and history, and a surprising talent for impersonating her sisters—she can mimic their appearance and mannerisms convincingly, a skill that becomes important in the story. Her endurance and quiet perseverance are also defining traits, allowing her to steadily work toward her goals without seeking attention.