It's a Wonderful Life.

Thunder (Ronald Cheng) is a God who likes to boast about his intelligence and business mind. One day, he was reminded by his girlfriend, the Saint of Nine Heavens (Qing Yan), that he had pledged his guardianship to a fat boy that he had saved thirty years ago. The boy will face the end of his life on New Year's Eve and it is now the time for Thunder to fulfill his pledge to resolve the boy's trouble.