Technology advances by leaps and bounds, and humanity grows ever more capable. People can soar through the sky, burrow into the earth, and summon wind and rain without even cultivating.
The immortals all go on strike and jump into the cycle of reincarnation to live as humans again.
The wind leaves, the rain leaves, the clouds leave...
Only the sun remains.
The sun is unhappy and refuses to work during the day.
So the human world relies on electricity for light.
A poor little beggar, so cold he can barely think straight, silently prays in an underground passage: "Grandpa Sun, Grandpa Sun, please come out! I'll give you the tastiest food in the world!"
Whoosh!
A handsome man, the sun, appears.