Misao Kusakabe is a supporting character in Lucky Star and a classmate of Kagami Hiiragi at Ryoo High School. She has been in the same class as Kagami and her childhood friend Ayano Minegishi for five consecutive years since middle school, though Kagami did not fully register her presence until their third year of high school. This persistent lack of recognition leads Misao to refer to herself and Ayano as a background duo, a label that becomes a running theme in her interactions.

Misao is a tomboy with a straightforward and energetic personality. She is simple-minded, bright, and deeply fond of the outdoors, spending much of her free time running as a member of the cross-country club. Her athleticism is her standout strength, and physical education is her strongest subject. In contrast, she has a strong aversion to studying and performs poorly in academic subjects such as mathematics and world history. She is also notably lazy in non-athletic contexts and can be quite forgetful, sometimes losing track of what she was about to say moments before.

A defining trait is her competitive but unfiltered social style. She speaks in a casual, masculine manner, uses the first-person pronoun watashi, and has a distinctive speech quirk where she adds a drawn-out va sound at the end of sentences. She is loud, friendly, and a little dense, and she eats in a clumsy manner that often draws attention. Despite her rough edges, she possesses a genuine, unguarded warmth that endears her to those who spend time with her.

Misao harbors a strong attachment to Kagami and becomes visibly jealous when Kagami begins spending more time with Konata Izumi, whom Misao views as a rival. She calls Konata by the nickname Chibikko and frequently argues with her over who has a closer claim to Kagami, even as she secretly borrows video games from various friends and plays them purely for fun, unconcerned about her lack of skill. Her philosophy of playing for fun rather than winning leaves Kagami both amused and bewildered when Misao enthusiastically praises her victories.

Her relationship with Ayano Minegishi is the most stable and long-standing in her life. Ayano acts as a caretaker figure, often reining in Misao's impulsive behavior and listening to her complaints. Misao also develops a more cordial relationship with Konata after graduation, when they end up attending the same university. Both are surprised to discover the other enrolled at a school neither expected the other to be smart enough to enter, and Konata begins calling her Misakichi in the manga.

In terms of development, Misao begins the series as a background character with little narrative weight, but her distinctive mannerisms, memorable catchphrases, and comic rapport with the main cast gradually elevate her to a regular supporting presence. After high school, she continues to appear in episodes set during university life, where her dynamic with Konata shifts from rivalry to a comfortable, teasing friendship.

Notable abilities include her stamina and physical endurance from cross-country running, as well as an instinctive, unfiltered honesty that makes her both blunt and charming. She has a notable instance of performing a dramatic role in a school play, revealing a surprising capacity for stage presence. Her most recognizable physical features are her short, messy dark brown hair, tanned skin, slightly slanted gold eyes, and a small fang that protrudes when she smiles broadly.