MC was so strong in a MMORPG he was labeled demon king by other players. He is invoked in his avatar body (OP power and equipment) by two girls, both saying being his true master, and him being their summon beast... which is actually a fail for them.
It's a ecchi harem, but I liked it. MC is actually a shut in and super awkward socially so he decided to continue with his Demon Lord roll-play (only way for him to "correctly" communicate)
Isekai Maou to Shoukan Shoujo Dorei Majutsu