After regaining all of his memories, Teruto focuses on taking part in Rebuild Battles so that he can reach Kikka as soon as possible. When he is one card away from completing the key, a boy in elementary school named Mikhail Saiki challenges him to a match. Mikhail is a formidable opponent who is also only one card away from challenging the King. However, Mikhail is surprised to see Hiyori with Teruto. Mikhail realizes that Hiyori is the kind girl that helped him the other day. What will be the outcome of Teruto’s final battle to complete his key?