But what after he killed the eight?

I fucking love this series, but don't y'all forget a tiny little detail? It's what everyone is getting their head steamin over in these new chapters: Where did he get his powers from?
Of course we know he got them from the sword that landed on his rooftop, but I kinda doubt it just fell off a plane or something. And what was with that imagery at the beginning, this memory-like vision of a medieval war with demonic looking monsters? And what's with the »Irregular Squad«-thingy at the end of each chapter - just a page from the scanlation-team or actually part of the story somehow? There must be more. I enjoy revenge as much as the next guy, but this one came with a little more than that, so I'm still wondering what that was all about. Can't wait to see. I mean, I want him to kill them bitches, but I also want information on that fantasy-part.