Final Fantasy: Unlimited Plot Summary: After their parents disappear, Ai and Yu read their parents' research and then decide to go in search of them. They ride a strange train to the Inner World and meet up with a girl named Lisa. Together, all 3 begin their journey within the Inner World. Ai and Yu, after reading their parent's research and after their parents' disappearance, they decided to go on search for them. They ride a strange train to the Inner World in search of their parents and meets up with Lisa in the train and together they begin their journey within the Inner World. Ai and Yu, after reading their parent's research and their parents' disappearance, decide to go in search of them. They ride a strange train to the Inner World and meet up with Lisa, together they begin their journey within the Inner World.