Fall into the Mortal World

I like this setting very much, but it is purely my own setting. Readers, please do not pretend to be other heroes~ The newly appointed Demon Lord came to the mortal world and became a five-year-old child in order to get rid of his anger. He was brought back to be raised by the master of cultivating immortals by accident. The master washed his hands and made soup to raise the apprentice. He was usually cold and did not like to play with others. It turned out that he was a demon cultivator, and the master expelled him out of anger. They met again three years later. Later, Master discovered that this "demon" was different, and they reached the same destination through different paths... Concept: sweet love