When do you really fall in love with someone? Because he held your hand without consent? Because there was no twinkle in his eyes when he said he loved you? Or was it just that Shenjian fell in love with him for a moment and had an indescribable feeling of déjà vu? This is an unsolvable question. Zhang Ziyu returned to the Dashen Dynasty hundreds of years ago. She met the inevitable person in the accidental world. The encounter was not perfect but it was the source of all her feelings and expectations about love. It was the memory of love that had been sleeping for thousands of years. Every girl you love is Zhang Ziyu. Who lives in your love memory and in which world he is.