Not sure myself as to the Sana and Miki event, though I suspect it has something to do with being infected by a meat parasite. Cless is the new NPC at the UNA College. Hope this helps.
I was actually just able to. I used seek in the abandoned base. However I haven't tried to get into UNA yet cause I couldn't figure out how to remove the indecent status.
Once you start the route for Cless you become able to go to the forest and defeat a certain beast and bottle it's drop to complete the rest of Cless's current route.