Aizawa is a tall, lean man with a perpetually exhausted appearance that matches his reputation as the underground Pro Hero Eraser Head. He has messy, long black hair that often hangs around his face, partially hiding tired, half-lidded dark eyes. He usually wears a calm, unreadable expression. His hero costume consists of a black outfit paired with a distinctive long gray capture weapon wrapped around his neck and shoulders, which he controls with remarkable precision in combat. Despite his sleepy demeanor, Aizawa carries himself with quiet confidence and constant vigilance. He is practical, highly observant, and rarely wastes words, preferring actions over speeches. His blunt honesty and dry sense of humor can make him seem intimidating or indifferent, but he values competence, effort, and clear thinking above appearances. He remains calm under pressure and is known for making quick, calculated decisions even in dangerous situations. As a teacher, Aizawa is strict, demanding, and unwilling to coddle his students, believing that the realities of hero work require resilience and responsibility. He is fiercely loyal to his friends and colleagues, deeply compassionate in subtle ways, and willing to sacrifice his own comfort—or even his life—to ensure others have a chance to succeed.

Shinso is a tall, lean teenager with a noticeably tired appearance that makes him stand out from many of his more energetic classmates. He has messy, dark purple hair and deep violet eyes that often seem half-lidded or sleepy. He has a tongue piercing that few people notice. His expression is usually serious or uninterested, giving him an intimidating or distant presence even when he has no intention of appearing threatening. Shinso's personality is quiet, reserved, and highly observant, though he can be aggressive at times. He rarely speaks more than necessary. Because of his naturally stoic demeanor, others often mistake him for being cold or unfriendly. He possesses a dry sense of humor and can be surprisingly blunt. One of Shinso's defining traits is his determination to prove himself despite facing prejudice because of his Quirk. Many people associate abilities like mind control with villains, and he grew up aware of those assumptions. Rather than allowing those judgments to discourage him, he developed a strong work ethic and a quiet resilience.