Ao Nishizaki serves as a core member of the disruptive school trio MM3, alongside Ushio Toujou and Namito Nagumo. He habitually skips classes and engages in delinquent behavior, yet demonstrates notable academic prowess through consistently high grades, suggesting innate talent. Within the group dynamic, Ao harbors romantic feelings for classmate Mimi Kitagami, mirroring Ushio’s attraction. However, Mimi exclusively reciprocates Ushio’s affections, leaving Ao’s emotions unreturned and fueling persistent romantic tension.

Characterized by a "princely" demeanor, Ao contributes to the MM3’s identity as charismatic troublemakers who frequently defy school regulations. Their antics consistently challenge Mimi in her role as class president.