The Accelerating Challenger (加速する挑戦者 Kasokusuru Chōsensha) is the twentieth episode of Phi Brain: Kami no Puzzle Season One and the twentieth episode of the anime series overall.
As Miharu has dinner with Nonoha, Kaito faces a deadly puzzle against Gammon, who seeks something known as The God Scrolls in order to complete the Puzzle of God. As Kaito nears the end of the puzzle, he sees a vision in which his friends die, which causes him to hesitate and make an error, though Bishop arrives and ends the puzzle before Gammon can win. The next day, Kaito sees more of his vision, predicting the destruction of the world if the Puzzle of God is solved. Believing this to be a vision of the future, Kaito resolves to solve the Puzzle of God himself.