Mahito is a young boy in wartime Japan who loses his mother in a hospital fire and struggles to adapt after his father remarries his aunt and relocates the family to his late mother’s rural estate. He shares a loving but somewhat distant relationship with his father, while being deeply cherished by his aunt and cared for by her maids.
At the estate, Mahito encounters a talking grey heron that leads him into a magical, otherworldly realm connected to his family’s past. This realm opens its doors to those in great distress and is inhabited by spirits and fantastical creatures—among them, the souls of those awaiting rebirth into the real world, and predatory pelicans that consume these spirits to survive.
Within this realm, Mahito meets his granduncle, the creator and caretaker of this alternate world. Weary and nearing the end of his life, the granduncle offers Mahito the reins of this seemingly perfect world. However, if Mahito accepts this offer, he will never be able to return to the real world.