"Baka and Test - Summon the Beasts" is set in Fumizuki Academy, a school with a unique academic hierarchy where students are divided into classes based on their test scores. Class A, the top tier, enjoys luxurious facilities, while Class F, the lowest tier, is relegated to dilapidated conditions. The protagonist, Akihisa Yoshii, is a cheerful but academically inept student in Class F, often referred to as a "baka" (idiot) by his peers. His best friend, Yuuji Sakamoto, is the class representative and a strategic thinker who devises plans to challenge the higher-ranked classes.

The school employs a system called "Summoner Test Wars," where students summon avatars called "Summoned Beings" to battle each other. The strength of these avatars is directly tied to the students' test scores, making it difficult for lower-ranked classes to compete. Despite this, Akihisa and his classmates frequently engage in battles to improve their standing and access better facilities. The series balances comedic and competitive elements, with the students of Class F using unconventional tactics and teamwork to overcome their academic disadvantages.

Key characters include Hideyoshi Kinoshita, a boy often mistaken for a girl due to his androgynous appearance, and Minami Shimada, a childhood friend of Akihisa who harbors feelings for him. Mizuki Himeji, a kind and intelligent girl who was mistakenly placed in Class F due to illness during her entrance exam, serves as a moral anchor for the group. The series also features recurring rivals from higher classes, such as Kouta Tsuchiya of Class A, who often clash with Class F in both academic and summoning battles.

The narrative explores themes of friendship, perseverance, and the absurdities of academic competition, often through exaggerated humor and over-the-top scenarios. The Summoner Test Wars serve as a central mechanic, driving both the plot and character development, as the students of Class F strive to prove their worth despite their low rankings. The series maintains a lighthearted tone, with occasional moments of heartfelt camaraderie and personal growth.