Chigusa Yuka attends a notoriously strict academy infamous for its brutal disciplinary measures. Ostensibly a reserved second-year student, she harbors a clandestine duality—two individuals, Yuka and Chigusa, masquerading as one to avoid detection. Their ruse begins unraveling when observant classmate Mayumi Takahashi detects inconsistencies in her behavior during a disciplinary inspection designed to expose the school’s mysterious vigilante protector.

The twins intermittently adopt the mantle of Kekko Kamen, a masked rebel who defies authority to shield peers from faculty cruelty. Their covert operations range from supplying tactical tools—like a ribbon neutralizing an adversary’s hypnotic physique—to engaging mechanized foes armed with electrified tentacles. While their interventions frequently safeguard Mayumi from escalating retribution, maintaining their shared identity strains peer relationships, at times igniting distrust or rivalry.

Subsequent disclosures expose Kekko Kamen as a collective of six operatives working to overthrow the institution’s tyranny. Though unconfirmed, contextual hints imply Yuka and Chigusa’s membership within this alliance, their collaboration culminating in the exposure of systemic corruption and the academy’s eventual closure. Their endeavors beyond this victory remain unrecorded in existing accounts.