(Papyton) Set after the pacifist ending, with the underground monsters and humans starting to interact. A lot of monsters still live underground in their homes, including the main undertale gang. Mettaton has started blossoming feelings for Papyrus, but is having problems not only opening up about his romantic feelings. But about his existence in the underground.

It's been eight months since the monsters emerged from Mt. Ebott, and tensions are higher than ever. Can monsters and humans really live together in harmony? In an attempt to help the two worlds merge, Ambassador Frisk created a program placing a select group of human candidates with a host monster family for six months. The end results could determine the fate of all monsters.