Responses
There isn't I think that was just a promo.
I'm not sure but I think this: http://www.mangago.me/read-manga/boku_no_heya_ga_dungeon_no_kyuukeijo_ni_natteshimatta_ken/ is the same as the one here but different. I think it's a newer version of this one.
I feel like there's a chapter missing.