Aichi and Kai's fight

What happens IF Aichi disappears after saving Kai from a collapsing building?
This is just an angst story that I've always wanted to find but no one has made a story like this. As you know, I like angst :D
The rest of the plot is the same in Legion Mate.
I just add my own story, but I'm not changing the Legion Mate's plot or what. That's it.