A drowned girl found by the MIS of the U. S. Navy in the Atlantic regained consciousness, but she lost almost all of her memory. A noble family from Aoki claimed her and arranged for her to attend the private Sui no Miya Academy in Saihara - but the additional condition was that she had to disguise herself as a man to enter the school.
From then on, pleasant, happy, excessive, sad and bizarre things began to happen. And she gradually discovered that her amnesia was just a layout carefully arranged by herself...