Hajime Kanzaki, a third-year Ishiyama High student and co-founder of the Tōhōshinki, commands authority as one of four delinquent leaders ruling the school through sheer force. His appearance embodies classic Japanese delinquent traits: dull blond hair tinged brown, pale skin, stubble, and listless eyes. Adorned with piercings—two on his left ear, a red stud on his right, and a lip ring chained to his ear—he sports a neck chain and a left-cheek scar, remnants of past brawls.

Beginning as a merciless enforcer, Hajime attacks allies and foes alike without hesitation, even flirting with lethal violence. Yet beneath his brutality lies loyalty to subordinates like Shiroyama and a guarded softness for his niece Futaba, whose brattiness he tolerates while shielding her from harm. His trademark yogurt drink ("yogurti") punctuates moments of casual dominance or quiet reflection.

When Tatsumi Oga seeks a malicious guardian for the demon infant Beel, Hajime becomes a target. Testing Oga’s loyalty by ordering Shiroyama’s defenestration backfires—Oga hurls Hajime instead, hospitalizing him and eroding his influence. Despite this humiliation, Shiroyama’s allegiance endures. During recovery, Hajime clashes with rival Tōhōshinki member Himekawa over petty disputes, cementing their contentious dynamic.

Regrouping with Himekawa and Oga, Hajime challenges Hidetora Tōjō, the group’s strongest leader, after their underlings defect. Though swiftly overpowered by Tōjō’s lieutenants, his pride fuels persistence. Transferred to Saint Ishiyama Academy, he retaliates against students who harm Shiroyama but is knocked out by Rokkisei’s Hisaya Miki. Expelled after interrupting a rooftop battle, he later joins a volleyball match against Rokkisei to avoid permanent dismissal.

Hajime’s arc shifts from ruthless overlord to a gruff protector with hidden depths. He acknowledges Shiroyama and Natsume as true comrades and earns Beel’s King’s Crest—a mark of loyalty to Oga granting supernatural strength. Pivotal acts, like rescuing Yuka Hanazawa and dismantling a device stifling Oga’s power, underscore his evolution into a steadfast ally.

His bond with Futaba unveils a playful protectiveness. He indulges her whims while feigning annoyance, like fabricating a Santa Claus lie to dodge her demands—a stark contrast to his hardened exterior.

Though retaining his hotheaded impulsiveness, Hajime increasingly channels his ferocity toward shared goals, whether training for volleyball clashes or battling supernatural threats. His journey from solitary tyrant to collaborative fighter frames him as a dynamic foil-turned-ally, balancing lingering abrasiveness with burgeoning camaraderie.