On their way to Fuuka Academy via ferry, Mai Tokiha and her frail brother Takumi rescue a girl stranded at sea. Their act of kindness is met with danger as the ferry is attacked by a foe who calls forth a monstrous machine. Despite her recent injuries, Mikoto Minagi wields a mystical sword to defend against the threat. As Mai delves deeper into this mysterious world, she uncovers that Mikoto is a HiME, a student with unique abilities tasked to shield the academy and city from enigmatic creatures known as 'Orphans.' Through various battles, Mai realizes her own HiME powers, enabling her to summon a powerful mechanical being named a Child. Alongside 12 other HiME, Mai embraces her newfound role, protecting her loved ones while facing an unknown adversary threatening the school and everything they hold dear.