Hikari, an optimistic and resilient magical girl with purifying and healing powers, wields love and light as her weapons, vowing to protect justice. Today, she receives urgent intelligence: the Demon King is about to invade the city and wreak havoc. To stop this disaster, she and a group of like-minded magical girls infiltrate the Demon King's stronghold—a sinister black fortress—intending to defeat him before he can establish himself.