Creatures that were created as an intent to create perfect artificial humans. The project became more than just to create the perfect artificial human, it became more of a hobby for the rich men to bet on them, gambling as they were pitted against other monsters to fight. It went on until the players finally gained awareness and killed off everyone in sight. Because of this, many players feel that humans mistreated them and that they are far superior and deserve better. It is revealed that Seiji has a formula to produce Corpse Riders, Player-like beings created from the corpses of recently deceased humans. Corpse Riders aren't as strong as Players, but they possess strength in numbers.