That Which Inherits Principles (迷宮にひそむ契約 Meikyū ni Hisomu Keiyaku) is the twenty-second episode of Phi Brain: Kami no Puzzle Season One and the twenty-second episode of the anime series overall.
After finding Jin a complete wreck, Baron explains to Gammon about how POG's leader, Count Pythagoras, intends to bring about a conflict between Kaito and Rook in order to open the gate to the Puzzle of God, while Kaito reads up on what Cubic had found on POG's network. Years ago, Pythagoras once attempted to achieve Phi Brain using Jin, who contracted with Orpheus and became a solver for POG. However, one day, Jin received a vision of the future, showing the world being destroyed by Pythagoras. Jin quit POG while Baron stayed to become a Giver, working together to find a way to prevent Pythagoras from achieving the God Scrolls. Two years prior to the story, Jin left to fight against Pythagoras in the Puzzle of God, though the results are unknown. As Kaito and the other files discover a hidden file on the POG network reading 'Pythagoras is dead', Rook appears before them, revealing he has been the one in control of the POG since Pythagoras' death half a year ago. As Rook reveals himself to be an Orpheus contractor, Kaito's vision shows that the one supposedly responsible for destroying the world is himself.