Approximately 300 years ago, Lailah, Emilia's mother, encountered and saved a young Satan from the verge of death after his tribe was destroyed by a random rogue demon. She supervised his recovery to full health, imparting much knowledge to him during the process. Before departing, she gave him a purple crescent-shaped crystal. Over the subsequent centuries, Satan rose to become the Demon Lord, recruited other demons into his army, and gradually united the demon race into a single empire using the knowledge Lailah had shared with him. He planted the crystal in a garden within his castle, where it grew into a tree. Throughout that entire period, Satan remained unaware that it was a Yesod fragment.
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