Killy is the boss?
How can?
I mean at the last fight, didn't they at different place? the boss at a meeting with that informant, and killy is fighting with that group?
Looking at the previous chapters, it seems like boss met the informant, then teleported to MC in chapter 6 (could've been before the events of chapter 5), fought, then jumped out of the window in chapter 7, met the informant again, and then made his way back to the base before the unconscious MC did.