Mio Serizawa, Kenta's classmate and Akemi's self-proclaimed best friend, possesses a notably irritable and volcanic temper. Her anger frequently flares in her facial expressions and interactions. Her speech patterns and overall attitude are rough, brash, and often confrontational or harsh.

Physically, she has blue hair cut to shoulder length and striking amber or yellow eyes, set against pale skin with a typical teenage build. She wears the standard school uniform, typically accessorized with earrings, a jacket, a necklace, and a string ribbon tie.

Beneath this volatile exterior, Mio demonstrates fierce loyalty and commitment, especially towards Akemi. She considers Akemi her closest friend but struggles profoundly to express these deep feelings appropriately, leading to complications. Her protective nature manifests through aggression and stubbornness. Mio exhibits distinct tomboyish traits: bravery, high energy, and an outgoing demeanor. She employs masculine speech patterns that reinforce her blunt, direct communication style. Her inherent stubbornness defines her interactions, making her resistant to changing viewpoints or backing down from conflicts.