A tomboyish girl. The only girl in a male-dominated family, with three brothers and her father. She started wearing boys clothes, as well as adopting a boyish haircut, when she was in first grade and after her mother was killed in a car accident. It is revealed in vol. 10 that part of the reason she chose to do so was because of the teasing in elementary school of a boy named Jôtaro Kai, who always bullied her, especially whenever her older brothers tried to protect her. Since then, she consistently wears masculine clothing, even to school, to the irritation of most of her teachers. Most of the girls at school idolize her and she is known for being mobbed every Valentine's day.

When Ito finds out that Makoto is a guy, she decides to help him and eventually falls in love with him. Throughout the series, Ito starts to become more feminine, because she wants to be the perfect girl for Makoto, at first unconsciously then with more intent.

Ito has various admirers such as Toki-sempai, two years ahead of Ito, who wants Ito to be much more feminine, become his girlfriend and go to college with him. Also Tsugumi-sempai, one year ahead of Ito, has an obsession with Ito, especially as a male figure, going so far as to call her "Ito-kun," a primarily male suffix. Finally there is Sakamoto, a "masochist" that likes both Ito and Makoto, after "running into" Ito during a class trip to Hokkaido. In volume 10 Ito meets Jôtaro again and he confesses that he teased her because he liked her. Ito is surprised; she remembers that she used to like him too, but she rejects him telling him that she is already in love with someone else.

As an actor, Ito relies on her raw charisma and physical ability rather than actual technical skills. She receives average grades in school though she appears to be abysmal at math. Her cooking skills are lacking, though the author has noted that Ito is good at "cooking for a crowd." She also is rather headstrong and doesn't think through situations before barging in, leading to some precarious moments with her admirers.

The characters for Ito spell out "thread," resulting from her father's wish for a name that is "slender and pretty" and her mother's wish for a name that "can be used to make something." Though Makoto's father considers her name a bad omen, as "a breaking thread," she considers it a blessing and as symbol of her creativity, which is consistent in the series.