Sans is the older, yet shy brother of Papyrus, and a member of the music monster of the underground. Once having began to live in the human world, Sans has become a fan of Boyfriend, who is a rapper, and wishes that he could rap battle against him, but he felt down and believed that this sort of dream is stupid, because he knows that this is not going to happen, and the fact that he is way too shy to even consider doing it, not to mention that he listens to music. He does not sing it. But when Boyfriend and his Girlfriend become missing, and with no one else to help out in trying to find them, it is up to Sans, the most shy and timid of the monsters to search for Boyfriend, learning to become brave in rap battle, and is now being watched over by his new goddess ally/crush.