The Legend of the First Rainbow
A farmer noticed that a wall he built keeps getting knocked down. He waits one evening and surprises three star maidens. Two are able to escape while one is left behind because the farmer hid her magic wings. They get married and have a son.
One day, the star maiden finds her missing wings hidden near their house, wears them and takes her son up to her sky world.
The gods take pity on the farmer and so they built a rainbow so that the mortal can sometimes climb up to the sky to visit his wife and son.