Kyosuke Shikijo is an average, somewhat timid high school student carrying a heavy emotional burden. His late father was a notorious
police detective who died in disgrace after being accused of corruption, leaving Kyosuke ostracized and struggling with his identity. Beneath his quiet exterior, however, Kyosuke possesses an explosive, highly repressed martial arts potential and a deeply unorthodox fetish. Kyosuke harbors an intense, secret attraction to the beautiful and aloof upperclassman, Aiko Hikasa, whose panties he inadvertently comes to possess.When a gang of brutal bank robbers terrorizes the city, taking hostages—including Aiko—Kyosuke springs into action. Driven by his desperate desire to save Aiko and fueled by a bizarre psychological transformation, he slips her underwear over his face. To his utter astonishment, this bizarre act unlocks a latent, superhuman state of being. The scent and fabric of the garment grant him incredible agility, godlike strength, and lightning-fast reflexes. Donning a makeshift S&M-inspired mask and gear, he transforms into "HK," the Forbidden Super Hero, and single-handedly defeats the criminals, rescuing the hostages and disappearing into
the night before anyone can identify him.As Kyosuke adjusts to his strange new double life, a wave of bizarre crimes hits the city, orchestrated by the psychotic and sadistic Mad Kosuke. A former martial arts prodigy gone rogue, Mad Kosuke seeks to plunge the metropolis into chaos and challenges the mysterious vigilante to a series of escalating, dangerous confrontations. Meanwhile, Aiko becomes obsessed with the enigmatic hero who saved her, unaware that the awkward boy sitting next to her in class is the man behind the mask.Kyosuke’s struggles are both physical and psychological; he must constantly find new sources of his unique power to keep up with Mad Kosuke’s brutal tactics, leading to numerous absurd yet high-stakes encounters. The climax culminates in a brutal rooftop showdown between HK and Mad Kosuke. Pushed to his absolute limits and suffering from a depletion of his bizarre energy source, Kyosuke must dig deep into his inner strength, confront the lingering trauma of his father’s tarnished legacy, and fight not just for his own survival, but to protect Aiko and the city he loves. Emerging victorious, Kyosuke restores honor to his family name, wins the admiration of Aiko, and firmly establishes himself as society’s most unconventional and effective protector, forever balancing his ridiculous powers with genuine heroism.