"Azumanga Daioh" is a slice-of-life comedy anime that chronicles the daily lives of a group of high school girls and their teachers over the course of three years. The narrative is episodic, with no overarching plot, instead focusing on the humorous and often surreal interactions between the characters as they navigate school life, friendships, and personal quirks.

The central character is Chiyo Mihama, a child prodigy who enters high school at the age of 10 due to her exceptional academic abilities. Despite her intelligence, Chiyo is often the target of playful teasing from her classmates, particularly from the eccentric and unpredictable Tomo Takino, whose competitive nature and loud personality create much of the series' comedic tension. Tomo frequently challenges Chiyo to absurd competitions, though her efforts are often met with failure or ridicule.

Koyomi Mizuhara, known as Yomi, is Tomo's childhood friend and serves as the more level-headed counterpart to Tomo's antics. Yomi often finds herself exasperated by Tomo's behavior but remains a loyal friend. Ayumu Kasuga, nicknamed Osaka, is a transfer student from Osaka whose dreamy, absent-minded demeanor and unique way of thinking add a surreal and whimsical element to the group dynamic. Her slow speech and bizarre observations frequently leave her classmates baffled.

Sakaki is a tall, quiet girl with a stoic exterior, often mistaken for being aloof or intimidating. Despite her cool demeanor, Sakaki has a deep love for cats, though her attempts to interact with them often result in comedic misfortune. Kagura, a sports enthusiast, joins the group later and becomes a rival to Tomo, particularly in physical activities. Her competitive spirit and tomboyish personality provide a contrast to the more reserved members of the group.

The series also features the girls' teachers, notably Yukari Tanizaki, their homeroom teacher, whose immature and often irresponsible behavior contrasts sharply with her role as an educator. Yukari frequently engages in petty rivalries with her colleague Minamo Kurosawa, known as Nyamo, who is more disciplined and responsible but equally prone to moments of absurdity.

The narrative unfolds through a series of vignettes, capturing moments ranging from mundane school activities to surreal daydreams and exaggerated scenarios. The humor derives from the characters' distinct personalities and their interactions, often highlighting the absurdity of everyday life. Themes of friendship, growing up, and the passage of time are subtly woven into the comedic framework, with the final episodes reflecting on the girls' graduation and the bittersweet nature of moving on from high school. The series concludes with a sense of nostalgia, celebrating the bonds formed during their shared experiences.