The Skeleton Knight's Crusade is a group of dark Duelists who use a "Shadow Sense".
The leader of the group is the Skeleton Knight, an urban legend incarnate. He first appears in Satellite after Yusei Fudo Duels and defeats Sect Ijuin. Sect, feeling pleased that Yusei now considers him as a rival, goes to the altar and performs the Sunset Salute. (This is a ritual where the Duelist asks the Skeleton Knight for cards.) The factory transforms into a temple and the Skeleton Knight appears and quickly defeats Sect, claiming "A loser shouldn't ask me for my cards". Yusei Duels and defeats the Skeleton Knight and after he asks for Yusei's name disappears. Sect later wakes up in Puzzle Hospital with a powerful dark card. It overpowers him, leading him to join the Skeleton Knight's Crusade.