Mikan, a young girl who was transported to a fantasy world of swords and magic at an early age, grows up to become a great mage and saves that world from destruction. However, she suddenly finds herself transported back to her hometown of Niigata! Having lost her magic and her friends from the other world, Mikan becomes a shut-in in her old room. Her older brother, Itsuki, who has waited ten years for her return, now does everything he can to show her the joys of this world and bring her back outside—but will it work!?