I'm not sure what happens next in Khemia, since only the first 2 chapters of that story have been released. I do not know (but hope/suspect) that each new story will be tied to Amicus's mission to get the galaxia to finally start working together and so each story will be named after the Sibling race he working with. Hopefully Amicus and the MC will get back together soon but I believe Khemia takes place about 2.5 years into the MC's eight year mission. So it may be the story after Khemia where they get together, depending on how the author decide to set the time line of each story.
That's why the Interea story is so nice, we get to see Amicus and the MC together, even if it is in the past.