He is the king with the least power in the underworld, but he voluntarily was demoted to the human world for the sake of the underworld; he is his follower, and in order to wait for his king to return, the two made a hundred-year agreement.
When he came to the world, there were people who were afraid of his soul and deliberately wanted to kill him, but there was only one person in the world who was willing to save him.
He is the only person in the underworld who is willing to wait for his return. He has waited for a hundred years, and a ghost lamp has been bright and dim by the Naihe Bridge for a hundred years; but he is not willing to give up for his own king.
The ghost lantern by the Naihe Bridge will always be on for you as long as you don't come back. The vow between you and me will never disappear as long as you don't come back.