WARNING: Major spoilers for Bravely Default ahead. If you have not played the previous game and do not wish to read the synopsis, skip past this section.
At the idyllic countryside village of Norende, Tiz Arrior lived an unremarkable but happy life. But all of this changed one day when the Great Chasm appeared out of nowhere and swallowed Norende whole. By some miracle, Tiz survived the catastrophe, but he had lost everything that he held dear.
As Tiz stood on the precipice of despair, a kind hand reached out to him. It belonged to Agnes Oblige, the vestal of wind. According to Agnes and her fairy companion Airy, the four crystals of Luxendarc had corrupted, possibly causing the Great Chasm and that only she could reawaken the crystals.
Thus Tiz decided to aid Agnes in her quest, but the pair were not without opposition. The duchy of Eternia-- bitter enemies of the Crystal Orthodoxy that Agnes hailed from--were determined to capture Agnes and prevent her from reaching the four crystals for reasons unknown.
While Tiz and Agnes took refuge in the nearby castle town of Caldisla, the duchy's men came violently pounding on their doors. In fear of causing trouble to the citizens, the pair decided to bring the fight to the duchy. Inspired by their actions, a frivolous man known only as Ringabel joined their cause.
This enigmatic man had lost his memory and the only clues to his identity lay in an even stranger black journal that seemed to predict the future, even foreshadowing his meeting with Tiz and Agnes. Although Agnes had her suspicions, she had no reason to refuse Ringabel's aid.
Together, the three traveled to the duchy's Caldislan stronghold to begin their assault. Then just before their battle with the Eternian commander, a surprising turn of events led to the Eternian second-in-command, Edea Lee, switching sides and assisting Agnes's group instead.
Afterwards, Edea explained that she was the daughter of the Grand Marshal of Eternia and how she had come to Caldisla to capture Agnes. However, during her relocation, she witnessed the atrocities of the duchy's army, leading her to doubt everything she had learned.
From there, the four unlikely heroes traveled across Luxendarc, fighting against the duchy at every turn and liberating the four crystals, one by one, from the enveloping darkness. During this time, their bonds of friendship grew and grew, until they became inseparable friends.
Upon awakening the fourth and final crystal, a massive pillar of light--the Holy Pillar--materialised in the south seas. Here, Airy performed the final, sacred ritual that would cleanse the world and close the Great Chasm, finally bringing true peace to Luxendarc.
After the ritual at the Holy Pillar, the four heroes woke up to find themselves back at Caldisla. However the strangest part had yet to come. After observing the town and its surroundings, it appeared as though time had rewound to the moment before the heroes first set out on their journey together.
This also meant that the four crystals had reverted to their pre-awakened state, effectively rendering the heroes' entire journey moot. Once the initial shock had passed, the four came to an unanimous, but difficult decision--they would travel again to awaken the four crystals.
Thanks to the experience gained along the way and the power of foresight, the heroes were able to bring light back to the four crystals much quicker than before. Soon, they were back at the Holy Pillar for a second time and anxiously prayed that Airy's ritual would be a success.
Unfortunately, their worst fears came true as they once again woke up at Caldisla before the four crystals had been awakened. By this stage, something was clearly wrong, but no-one knew what . With no other options available to them, the four painfully set out to awaken the crystals for a third time.
Along the way, it was Ringabel of all people who realised the truth of their predicament. Time itself wasn't going backwards, but rather the four were being propelled to parallel universes. The ultimate proof was Ringabel himself--he was in fact the Dark Knight Alternis Dim from the world before the "first".
With this newfound knowledge, the heroes continued to rescue the crystals in the third world, then the fourth and finally the fifth. Just when the cycle seemed to repeat endlessly, something changed at long last, but it was something that the heroes never wanted to see.
After performing the ritual in the fifth world, Airy revealed the truth. The lying fairy had played the heroes like a fiddle--everything they had done thus far was not to save Luxendarc, but instead to doom it. Each time they summoned the Holy Pillar, they ripped a hole between worlds.
Now, Airy had linked countless worlds and it was finally time for her master to descend upon the realm. Known as Ouroboros, the God of Destruction, this nefarious villain seeked to consume the myriad Luxendarcs to attain enough power to challenge the gods that resided in the Celestial Realm.
Intent on stopping Ouroboros, the heroes of light fought their final--and most difficult--battle. However, their efforts proved futile against the might of a god that could destroy entire worlds to replenish his energy. Just when they were prepared to give up, a ray of hope shone from beyond.
Each of the four heroes from all of the parallel Luxendarcs banded together to wrestle free from Ouroboros's control. With the hopes of all the Luxendarcs riding on their shoulders, the heroes locked in combat with Ouroboros regained their strength and, in the end, struck down the god.