As in the story of Adam and Eve, this world is full of "fruits" of godly knowledge. They allow people to do things that are beyond normal human knowledge, so they are referred to as "Unknown." To use them, one needs to be in a pair, an "Eve" who knows the fruit and can dispense its knowledge, and an "Adam" who can use its power. Ox and Iwan are one such pair, and they're tracking down and gathering all of the other "Unknown," but what is their final goal?