Mikan, a young girl transported to a world of swords and magic, grows up to become a great mage who saves that world from crisis—only to be sent back to her hometown of Niigata. Having lost her magic and companions from the other world, Mikan becomes a shut-in. Her older brother, Itsuki, who has waited ten long years for her return, does everything he can to show her the joys of this world and gently coax her outside—but will he succeed...!?