Ut Sans, Us Papyrus, and Ss Chara after cooperating with each other finally defeat the human once and for all and end up freeing themselves from their prison, they ended up in the Mainframe where they are met by Error 404 Sans the God of the Undertale Multiverse. He tells them that the human they defeated is not gone but is sent to a different world where they could end harnessing Lv and come back to confront them once more as they agree to help as 404 sent them to the world the human is in and they must stop them for all cost but it isn’t the human that is the only threat in this world...there's more and they need to be ready.