Energetic, cheerful, and tomboyish high school girl Madoka Misaki fights as Pure Noir, the Black Merpyua warrior, empowered by the fairy Nuupo. She constantly battles dark sorcerers and monsters, serving as the core member of her team. During one fierce battle, her ally Pure Blanche, the White Merpyua warrior, is captured by the enemy's female commander, Jabaria. Determined to protect her comrade, Noir launches a solo assault on the enemy base—an action far more dangerous than anticipated. This story tests her growth, her resolve to fight, and the bonds she shares with her teammates.