100-man no Inochi no Ue ni Ore wa Tatteiru EP12 - A Murderer’s Summer

As her reward for completing the quest, Tokitate gets to ask the Game Master whether this alternate world is actually virtual or not... and the answer is that it's an alternate Earth that branched off of the original Earth's timeline. Upon hearing that it's an existing world, Yotsuya trembles with the realization that he killed real people. Once he returns to the real world and resumes his normal life, the Game Master appears before him in the form of a young girl and leads him to a meeting with the next new player.