On the other hand, Sophia's master (who I assume is the Demon Lord) specifically asked Sophia to not go after Oka, but Potimas was fair game. To me this suggests that Demon Lord is at the very least a Reincarnator or administrator or some description. I admit that it doesn't directly prove or disprove Kumoko=Demon Lord.
My bets are still on Kumoko being the demon lord though.
Sophia is probably that shady girl in the OP standing behind the rest of the characters.
Random cuts from the cloaked person with slicing wheels this episode seems to be the crazy "If you see someone with Taboo let me know" girl.
Sophia mentioned "Don't give me that no-killing crap considering how many you've killed." Seems like Oka has been playing world-police when she tried tracking down all the reincarnators with power and determining whether or not they were "suitable" for the world etc.