Jiang Qianqian discovers that one wall of her bedroom actually connects to a secret chamber, locked inside which is a scarred yet extraordinarily handsome Demon Lord. To rescue him from predicament, she steps into the secret chamber again and again, only to find that this dangerous yet gentle man has already secretly loved her for a thousand years. She thinks this is the whole truth, little knowing that a thousand years ago to save her, he almost exhausted his divine soul. Now, his true body cannot leave, but his spiritual consciousness avatar accompanies her into the modern world, spending heartwarming nights one after another. It turns out this encounter spanning a thousand years is not her accidentally breaking into his world, but him waiting for her for a thousand years, and with his long life, loving her for a thousand years.