The Bravely Default series has a tradition of secret twists that break the fourth wall and require a little pluck and ingenuity to solve. Bravely Default 2 is no exception, hiding the true ending behind a series of riddles and clues. If you're looking to 100% the game with all of the jobs unlocked and see the true ending to the quest. Bravely Default 2 spoilers follow.
How To Reach Chapter 6
If you're wondering how to reach the true ending, you've probably already gotten to Chapter 5 and defeated the fake-out final boss, the fairy Edna. The game makes it fairly clear that there's more story to uncover, with a cliffhanger of an ending that leaves the major threat still unresolved. Edna tapped the power of an all-consuming darkness called Night's Nexus as part of her plan, and even after defeating Edna, the Nexus lives on. Gloria sacrifices herself at this point in the game, leading to the game's credits.
However, once you save your cleared game file and reload it, you'll see a new cutscene that drops a conspicuous clue about what you should do next. Instead of moving forward to confront Edna, your party can conclude that there's something more to be done and leave the area. That will trigger the start of the game's actual finale, Chapter 6.
The Hidden Village of Mag Mell
Once you've reached Chapter 6, you'll be able to access a new area, the town of Mag Mell. The fairy village is hidden from human sight, but Adelle suggests they might be helpful to defeat the Nexus, so you can now visit them in-person. Go to Wiswald Woods and Adelle will walk you through the process of locating the village. Aside from being important for story completion, Mag Mell also has high-level equipment and items for sale, along with new sidequests.
When you've reached Mag Mell, you'll be prompted to visit with the queen of the fairies, Esmeralda. She'll unlock a new final dungeon, where you can do battle with the real Night's Nexus. This is a much tougher boss fight, and ultimately leads to another sad ending. Gloria survives the encounter this time, but the fairies tap all of their collective power to imprison the creature--which means Adelle is left behind. That makes this the second fake-out ending, and of course, there's more to unlock.
The Bravely Default series has never seen a fourth wall it didn't intend to break.
The Bravebearer Asterisk
Once again, when you load your cleared save file, you'll get a hint of where to go next. This time, the cutscene shows you Sir Sloane, who held the heroic mantle in the prior generation and sacrificed himself earlier in the game. Make sure you have every job including the two optional jobs, Salve-Maker and Gambler, and then go back to where you buried Sir Sloane at the Vale of Sighs. You'll get more story details followed by another boss encounter against a youthful Sir Sloane. Defeating him will get you the game's final job, the Bravebearer Asterisk. With this powerful new job in tow, you finally have the tools to defeat the game's true villain.
Kind of. Almost.
How To Power Up Your Other Asterisks
But wait! Before you go barreling headfirst toward the final encounter, you may want to unlock the level cap for your various jobs. Those will enable some of the most powerful abilities in the game, and it will be vital to completing the adventure. To find these, look for glowing purple portals scattered around the overworld. Each one will have you take on a group encounter with much tougher versions of previous Asterisk bearers, which will then unlock more powerful job levels and abilities for all of your existing jobs.
One More Thing...
Finally, once you feel properly equipped to take on the final encounter with the Bravebearer and other jobs powered up, there's one more thing you need to do. You see, the Night's Nexus relies on being remembered to keep coming back, which is why it can never truly be defeated. And here's where we reach Bravely Default 2's moment of breaking the fourth wall. Since it needs to be remembered to draw power, you need to erase it from your mind to be able to defeat it. And by "erase it from your mind," we mean overwrite its save file.
When you go into the save menu at this point, you'll see a new save file at the bottom that you didn't create. It's creepy and glows purple and just looks, you know, evil. Attempting to save over this file will warn you that overwriting it cannot be undone, but go ahead and do it. This will trigger events leading to the rest of the game. You'll get more story details, go back to Halcyonia to meet up with an NPC you talked to dozens of hours ago, and then enter yet another, really for-real final dungeon. Here, you'll face the Night's Nexus in her true form, and defeating her will trigger the true ending.