Legends
In the heavens there is a giant tree, and from this trees grows stars. However, the stars are only grown once, and the tree never makes them again. The tree releases the stars into the night sky, but before day arrives the stars must be returned to the tree, or else they will eventually die. When any stars go missing, the tree stops prolonging the lives of all the other stars until the missing star is returned. If the lost star is never returned, then eventually all the stars will die and the universe will go dark forever.
Story
Lin Yue Ru was a star catcher, aka someone who rounds up stars after night is over and returns them to the tree. One day, Sirius, the brightest star in the sky, went missing. She was accused of stealing it and trying to cause chaos in heaven so she was promptly kicked out and punished. It was then decreed that anyone who found the missing star would have one wish, no matter how ridiculous, fulfilled. While Yue was allowed to keep her job, she got demoted to rounding up lower level stars. Now she must try and find the missing star before anyone else does so that she can prove her innocence and get her life back to normal!!
disclaimer: wow I'm sorry for my extremely shitty writing and I know it makes no sense because the sun is a star too and it's not like the stars only come out at night BUT IT'S JUST A STORY OK DON'T JUDGE ME :(