The Philosopher is a character whose existence was revealed in Guilty Gear Xrd -SIGN-. He was an ancient sage that went to the Backyard and came back alive. To prevent evil from going there, he created a tome with all the information and findings within the Backyard and locked it up in an unknown location, saving the world. However, he could never predict that, many years later, it would not be evil that would find the Backyard, but that evil would come from the Backyard itself.