The two met in a case, and one of them died bearing all the charges.
Another person took their memories and became the princess's son. He met the dead person, but he lost his memory and could not remember him.
That person became his book boy
He lived until he was 25 years old, and the book boy accidentally fell into a cliff, and he jumped. As a result, the two of them traveled back in time, but the book boy's memory still remained in the ancient times.
Intention: Write as soon as you think of it