Gakuho Asano, the board chairman of Kunugigaoka Junior High School and father of Gakushu Asano, possesses neatly combed brown hair and brown eyes that appear violet in the anime. He is consistently attired in a formal brown business suit, setting him apart from other staff, and wears a sawtooth leaf pin on his tie, a gift from his former cram school students. In his youth, his hair was strawberry blonde, and during his cram school years, it was an unkempt style that reached his ears, resembling his son’s, and he dressed more casually.

His personality is defined by an intense fixation on perfecting his educational methods, prioritizing his system above morality or the future. This drives him to employ underhanded tactics, such as suggesting Class A poison Class E’s food or personally brainwashing students to preserve his system. Yet he respects the integrity of earned academic results, allowing honest placements even when outcomes disfavor him. He maintains a relationship with his son rooted in relentless pressure for flawless victory, treating Gakushu as a tool and mocking his failures.

Previously, Gakuho’s teaching philosophy mirrored Korosensei’s, emphasizing kindness and engagement, including allowing mock assassinations for free time. The suicide of a beloved student due to bullying caused him to reject this approach. He exacted revenge by ruining the bullies’ lives, turning them into gambling addicts, and shifted his methods to cultivate "strong" adults through Kunugigaoka’s discriminatory class system.

He established Kunugigaoka Junior High from a cram school, constructing a new campus to escape past failures. Demonstrating high intelligence and athleticism, he once defeated a karate blackbelt in three days through observation and strategy. He married and had a son, Gakushu, though their relationship grew competitive rather than familial. He worked well with Aguri Yukimura, the former Class E teacher, and later scrutinized a transfer student who deliberately destroyed property to be sent to Class E.

Gakuho initially permitted Class E to attempt assassinating Korosensei for government funds but intervened when their influence threatened his system. He engaged in direct conflicts with Korosensei, rigging exams and coaching the baseball team, conceding defeat when outmaneuvered. He dismissed teacher Akira Takaoka for brutal methods and failure. As Class E consistently outperformed Class A, Gakuho escalated to brainwashing Class A students for finals, inciting intense bloodlust. After their defeat, he attempted to kill Korosensei with grenades, but Korosensei protected him, prompting Gakuho to reflect on his methods and partially revert to his earlier principles, though he retained his system without further direct intervention.