Daigo Minamikokubaru is a lively second-year high school student with a bubbly, sometimes excessively enthusiastic personality. His shoulder-length brown hair, brown eyes, and slim, pale frame are often clad in a standard school uniform—white shirt, brown tie, black trousers—though he occasionally swaps it for casual wear. Born on June 5, he navigates the unique challenge of having his mother as his homeroom teacher, a dynamic that sparks frequent classroom scoldings when he addresses her as "mother" or poses cheeky, off-topic questions.

Though mischievously vocal about his admiration for women, particularly those with larger busts—a habit earning him sharp reprimands from female peers—Daigo balances his playful antics with unwavering loyalty. He orchestrates schemes to support friends, like reuniting Kazuma Hoshino and Madoka Kōmoto to revive their childhood bond. His instant friendship with transfer student Kazuma, whom he dubs "bro," mixes camaraderie with light envy over Kazuma’s accidental romantic success, yet Daigo remains a reliable ally.

A year after the main storyline, an OVA highlights his comically persistent quest for a girlfriend to join him at a school festival, showcasing his undeterred romantic aspirations despite habitual missteps. His interactions with classmates Ui Nakatsugawa, Ibuki Hinata, and the Tōdou sisters cement his role as a humor-driven social catalyst, stirring playful chaos while fostering camaraderie.

Rooted in familial and school dynamics, his character consistently blends humorous flaws—like tactless remarks—with sincere devotion to friends, maintaining a focus on school-life escapades and romantic fumbles without expanded backstories.