The game begins soon after Marche moves to St. Ivalice, the country town where his mother was born. The reason for the move was twofold: Marche's parents' divorce became final after many years of separation, and they had to leave the home where Marche grew up. In addition, Marche's little brother Doned found that his illness was getting worse, and the family figured a move to the countryside might be good for him. But when all of Ivalice changes, Marche's adventure begins. Will he be able to restore the world to the way it was before? Online Description

Marche and his sick brother Doned moved into St. Ivalice following their mother, who believed that a change in environment would be good for Doned's health. The Radiuju family had lived in a hot place where it practically never snowed.

At school, Marche receives the nickname "New Kid" by the bullies Lyle, Colin, and Guinness, and is teased for being quiet like "a little girl." Marche ignores the bullies and befriends Mewt Randell and Ritz Malheur, the Class Head. After school, Marche and his new friends meet at his house to look at Mewt's new book on monsters and magic. While reading it with Doned, the kids think it would be great if a game world like "Final Fantasy" was the real world. As the kids sleep, St. Ivalice transforms into a dream Ivalice, and the snowy landscape changes into a hot climate filled with fantasy creatures.

When Marche wakes up he finds himself stranded in a strange land. Unintentionally offending a bangaa, Marche receives Montblanc's help who becomes his guide in the country called Ivalice. Marche joins Montblanc's clan, Clan Nutsy, and makes it his mission to return the world to normal and to find his friends.

At first, Marche just does the odd mission, but is eventually transported into a strange dimension where he finds a Crystal. Before he can approach it, a being known as Famfrit appears, proclaiming himself a Totema, a defender of the Crystal. Marche defeats the Totema, and after Famfrit joins his cause, the Crystal shatters and an image of Mewt in pain appears. A voice tells Marche that what he destroyed was one of the world threads, and that if all are destroyed a new world would be born. Taking this as a hint on how to get his own world back, Marche resolves to destroy the world threads.

Marche's next mission introduces him to the famous Ezel Berbier, who is under attack from several warriors aligned with the Judges. After helping Ezel, Marche is shown the power of the Anti-Law cards. From then on, Ezel considers Marche a close friend and valuable customer.

Marche finds the next world thread at Roda Volcano when a violent earthquake opens the portal to the Crystal, which Marche blindly leaps in to. He is confronted by the next Totema, or at least one of its forms, the Ultima Crystals. Upon defeating Ultima and shattering the Crystal, another image of Mewt appears demanding to know who is trying to destroy his dream world. When Marche returns to Ivalice, he starts to have second thoughts about destroying his friend's world.

When Marche is ordered to find a ghost he enters the Nargai Cave, and finds some kind of spirit. While following it, he is pulled into another portal and into a crystal chamber. The ghost is here too, but is absorbed by the Totema, Adrammelech, who claims only his master may approach the Crystal. After defeating Adrammelech and shattering the Crystal, Marche finds himself back in the cave where Babus Swain is waiting for him. Before Babus can do anything, another image of a pained Mewt appears. Babus asks Marche whether it is worth causing Mewt so much pain to revert the world, even if it is not real.

Later at Muscadet, Marche finds Judges taking away people for questioning, as they look for the people trying to destroy the world. When Marche sees a moogle being mistreated, he runs in and claims he is the one they are looking for. The Judge questions this and sends in some units to see if he truly is whom they want. Judgemaster Cid appears and concludes that Marche is indeed the boy they are after, and takes him in for questioning.

Cid demands to know why Marche is destroying the world threads when another portal opens, taking in Marche, Cid, and Babus. Inside the chamber Marche concludes this Totema is severely weakened, as the Exodus Fruit can do nothing. Babus vows he will not allow anyone to destroy the Crystal and tries to defend Exodus. Upon destroying all the fruit and Babus, the Crystal shatters, and Marche and Cid are exposed to a scene from their past, causing Cid to regain his memories. Realizing that what Marche is doing is right, Cid allows Marche to leave.

Marche finally finds his brother, Doned, who has regained the use of his legs. Instead of being equally happy to see his older brother, Doned runs to the nearest clan group and turns Marche in. Dumbfounded, Marche fights off the group and wonders what is wrong with Doned.

When Marche encounters the mysterious Llednar Twem they are pulled into another crystal chamber where Llednar tries to kill Marche with his ultimate technique, Omega. Cid appears and uses an Anti-Law to disable it. The two engage in battle, but Marche is no match for him. When Llednar breaks a law Cid red cards him and sends him away. Proceeding to the crystal chamber, Marche is confronted by the final Totema, Mateus, who tries to trick Marche out of his will to fight. When Mateus is defeated, the Crystal shatters, but the world does not change back. The voice of Queen Remedi proclaims that even without the Crystals, the world will remain as long as someone wants it to. Realizing his friends want this world to stay, Marche sets out to convince them to revert it.

Knowing that the palace is having an audience day, the clan sets out to get a gift: some Materite. In the Materiwoods, the clan is ambushed by a group of viera bandits who knew Marche would be there, Marche realizing Doned had alerted them. Doned appears in person and claims that he does not want to go back since he has nothing and Marche has everything, shattering the Materite the clan had come to claim. Doned runs off, while Marche exclaims that Doned did have something he had always wanted.

They make a gift in time to present to Mewt, but are ambushed in the palace waiting room by the castle guards. Babus appears to help them, wanting to know more about the other world. Taking them to the throne room, Marche approaches an angry Mewt and tries to reason with him, but is cut short by Queen Remedi, who teleports Mewt away. They are confronted by Llednar, who is invincible to anything they throw at him. Cid arrives causing Llednar to run away, and Babus and Cid promise to find where Mewt has gone.

Marche searches for his brother. He goes to a mythril vein and starts digging, which gets Doned's attention. After disposing of his goons, Marche tells Doned that he envied all the attention he got, and that he wishes he was as loved as him. Doned realizes it is wrong to be selfish, and agrees to help Marche revert the world.

Marche learns Mewt is hiding in Ambervale. On the mountain path he is confronted by his other friend, Ritz, who wants the fantasy world to stay and attacks. Upon her defeat, she accepts her fate and allows Marche's clan through. At Ambervale, Marche has one final engagement with Llednar, and using Ezel's ultimate Anti-Law, dispels his protection, allowing him to defeat Mewt's evil side once and for all.

Marche confronts Queen Remedi, and knocks her out. He attempt to convince Mewt the world is not good for him and that they should go home. Before Mewt can be fully convinced, Queen Remedi reveals her true form, the Li-Grim, the final world thread and the collection of all the world's wishes. Marche defeats her, convincing Mewt to return them all home. Mewt summons the Gran Grimoire and takes them back to the snow-covered St. Ivalice and they learn to appreciate their lives outside the realm of fantasy.