In the early part, it doesn't have much to do with time travel, but later the two are closely intertwined. This is my first time writing this kind of story, and some of the logic may be hard to make consistent, so I hope everyone won't be too strict.
The setting is also a little different from reality, and I may not be able to tie up every loose end very well. Please go easy on me.
Theme: Cherish the people you have now
