Futaba Kutsuki is brought to Kanenone Academy against her will, where she immediately establishes herself as a tomboyish protector of the female students with a pronounced aversion to men. Outwardly rebellious, short-tempered, and a self-proclaimed misandrist, she embodies the classic tsundere archetype, using her tough exterior to mask an inner conflict and vulnerability. Her behavior is particularly disgusted by the perverted antics of the so-called Baka Trio, a group of boys notorious for their indiscretions. Futaba does not hesitate to resort to physical violence against them as punishment for their actions, going so far as to knock out and hang them upside down by a rope when they are caught peeping on the girls while they bathe. Because of her strong and combative personality, other female students tend to see Futaba as their natural leader and self-appointed guardian against the male population of the school.

Futaba has a younger sister named Wakaba, whose temperament is quite different from her own. Wakaba is friendly, naive, and openly enthusiastic about the school, often contrasting sharply with her sister's hostility. Despite their differences, Wakaba holds a deep respect for Futaba, referring to her with the honorific onee-sama. In terms of appearance, Futaba stands 164 centimeters tall with a slim build, long violet hair, and red eyes. Her clothing frequently defies school regulations; she is often seen with her uniform shirt open over a tank top or a hoodie, an outfit choice that emphasizes her rebellious and tomboyish nature.

The rigid stance Futaba holds against boys begins to fracture primarily through her interactions with a male student named Yuusuke Takasaki. An early act of chivalry, where Yuusuke discreetly hands her a towel to protect her modesty after her shirt becomes see-through, makes a strong impression on her. The turning point for her character occurs after the Baka Trio pulls a cruel and humiliating prank on her in revenge for her constant attacks. Devastated and angry, she decides to leave Kanenone on her own that very night. She becomes lost in the woods and sustains an injury, but she is rescued by Yuusuke, who carries her back to the school. This act of kindness, combined with his earlier display of respect, sparks deep romantic feelings inside Futaba for a boy for the first time.

This development marks a significant shift in her personality. She starts as a stereotyped tough girl caricature and gradually becomes a sensitive, shy, and kind individual, undergoing what viewers describe as a complete 180-degree change over the course of the series. Her motivations evolve from being a guardian who simply wants to cause trouble for males to a young woman who struggles with her newfound feelings. Six months later, in the continuation of the story, she maintains a correspondence with Yuusuke but finds it difficult to confess her love. A supernatural event involving another character named Midori helps Futaba and Yuusuke acknowledge their mutual attraction, and they officially become a couple. Beyond her physical combativeness, Futaba possesses a subtle supernatural awareness. Her family has a tradition of producing onmyoji, traditional Japanese occultists, which grants her a sensitivity to uncanny phenomena even if she does not fully understand these spiritual powers.