Octopath Traveler 0: How to reach the hidden island of Agapea and complete An Indestructible Flame

This guide page will have some near-end game spoilers for Octopath Travler 0

You've reached the near end (or maybe even the very end) of Octopath Traveler 0. You've recruited the final character, but you cannot complete their personal quest "An Indestructible Flame", because you don't know where it is - it never showed up as an objective. Similarly, if you look in your Construction menu in Wishvale, you may have also seen a Strange House option that requires a 'Strange Key', located in Agapea.

How do you complete "An Indestructible Flame"? Where is Agapea? Turns out these two things are related.

The key thing is this. You need to find "A Priestess's Journal", which appears in the Skies of Vanity section of the Heavens final dungeon area.

Just northwest of the center area, you can find this journal at a dead end on one of the paths. It's easy to miss, and if you didn't see it earlier.

The images below will point you to the right spot.

If the journal is not there, you may need to continue further in the story for it to appear, although we have verified that you do not need to be on a clear save file to read the journal. Once read, you'll unlock the Side-Story quest "The Hidden Isle".

That's pretty much all you needed from this guide page, I imagine. Follow the objective markers for "The Hidden Isle", to make it to the land of Agapea, which should give you the Master of Orsterra trophy & achievement for traveling to every location on the map, unless you are missing an island or dungeon somewhere else.

On Agapea, you can collect more Path Action goodies and shops, and such. "The Hidden Isle" quest will end and move onto the next quest, "An Indestructible Flame", which requires both Sazantos and Rondo. You'll have to defeat a boss called Demon's Blade Curse, but at this point in the game, you should know how to handle yourself.

Once you've completed these quests, completed the game, defeated the post-game boss, and built the Strange House (and recruited Isla), you'll finally be able to enter the Tavern of Nil from the Strange House, which will allow you to pick up the last Music Scores for your collection.