Mai Toba and her younger brother Takumi are waiting to be arrested on a swaying cruise ship. Their destination is a high school called "Fuuka Academy". Mai, whose parents have both passed away, unexpectedly received a scholarship from Fuuka Academy and decided to transfer to this school with her younger brother. While sailing on the sea, Mai suddenly found a girl drifting on the sea. The girl holding a big sword is called Mibukuro Mita, and Mai rescued her on the ship. Then, a mysterious long-haired woman named Natsuki Kyuuga appeared on the ship. After seeing Mita, Natsuki immediately wanted to take the other person's life and summoned a mechanical beast to participate in the battle! Mai was shocked by the scene in front of her, but at this time, her superpowers also awakened! It turns out that Mai is also a superpower with "HiME power". After the battle, Mai and her younger brother Takumi continued to move towards Fuuka Academy, but they didn't know that what was waiting for them there was the secret of HiME power and the shackles of fate.