Eighteen years ago, a powerful monument was discovered on a mysterious island. The monument contained data only certain people could extract, who then became students of the island's school. By extracting the data, the students are able to summon a creature that they can fight with. Of these people, Satou Taketora is your typical lazy kid who doesn't do anything. Hence, he's ranked dead last. But one day, he's dragged into a battle with his old childhood friend, and to everyone's surprise...his summon has more than meets the eye...