This is a fairy tale (big mistake) between the little prince of the King of Sun and Xiao An, the King of Darkness.
The King of Sun and the King of Darkness are the two kings of the Kingdom of Aite.
The King of Sun lives in the sun, wears beautiful clothes, and manages everything in the country, but he does not know the existence of the King of Darkness. The King of Darkness lives in the darkness, wearing ragged black clothes, peering from the underground to see what's happening on the ground, and his job is only to end the lives of dying people. He is the only one in his country, and no one lives with him in the cold underground.
Only when performing his work does the Lord of Darkness have the opportunity to go to the surface and come into contact with a world that is completely different from the underground and full of life.
The little prince, who is best at thinking things through, sometimes thinks that Xiao An is an assassin sent by his younger brother to assassinate him, and sometimes thinks that he should be a poor orphan, causing Xiao An to mistakenly think that the little prince suffers from multiple personalities.
By accident, Xiao An becomes the little prince's exclusive undercover agent.
The protagonist may be a bit of a villain or a novice, so be careful before entering.