Futaba Yoshioka is the central character of the story. Her background is defined by a painful experience in middle school, where she was ostracized by her female classmates because they were jealous of the attention she received from boys due to her naturally cute and feminine appearance. The only boy she liked during that time was a gentle and small-statured classmate named Kou Tanaka, who shared her feelings. However, after he invited her to a summer festival, he failed to appear and subsequently moved away without saying goodbye, leaving Futaba with a deep sense of loss and regret.

Entering high school, Futaba's personality has undergone a drastic, self-imposed transformation. Determined to avoid the isolation she suffered in the past, she deliberately suppresses her true feminine nature and works to appear as unattractive and unladylike as possible. She alters her behavior, walking in a slouched manner, speaking less delicately, and showing little care for her physical appearance. On the surface, she is strong-willed, stubborn, and passionate, but this hard exterior masks a deep-seated fear of being disliked by her peers. Her primary motivation is to make genuine female friends and lead a quiet, unremarkable school life, even if it means sacrificing her true self for the sake of acceptance. This strategy is challenged when she comes to realize the friends she initially makes are merely "placeholder" companions who do not truly value her.

Futaba's role in the story is set into motion when she reunites with her first love, who now goes by the name Kou Mabuchi. He has changed from the gentle boy she knew into someone who is cold, sarcastic, and seems indifferent. This reunion forces her to confront her past and re-evaluate her present choices. As she reconnects with Kou, she begins to break free from her self-imposed disguise, taking on the role of class representative and forming a genuine, supportive friend group that includes Yuri Makita, Shuko Murao, and Aya Kominato. Her most significant role is as a catalyst for Kou's healing; after learning that his bitterness stems from the death of his mother, she persistently tries to reach him, urging him to allow himself to feel joy and excitement again.

Her key relationships are central to her development. Her relationship with Kou Mabuchi is the emotional core, evolving from a nostalgic first love to a complex present-day connection where they help each other grow. She forms deep and supportive friendships with Yuri Makita, with whom she shares a mutual affection for Kou but prioritizes their bond as girls, as well as with Shuko Murao and Aya Kominato, who become her circle of honest and caring peers. Her brief relationship with Toma Kikuchi serves as a crucial turning point, as she realizes her feelings for Kou cannot be set aside, leading to an amicable breakup.

Throughout the story, Futaba undergoes significant development. She begins as a girl hiding her true identity to fit in and evolves into someone who learns to live honestly and face the world as her authentic self. She transitions from being indecisive and afraid of others' opinions to becoming someone who can assert her own feelings and make difficult choices, such as ending a relationship to be true to her heart. She learns that true friendship is built on sincerity, not on self-effacement.

Regarding notable abilities, Futaba excels in chemistry but struggles with English. She consistently carries a sewing kit with her, highlighting her practical skill in sewing and mending things, a reflection of her caring and hands-on nature. She is also noted for her perceptiveness, possessing a strong ability to analyze people and situations accurately, though she can become frustrated when she fails to understand someone completely.