Octopath Traveler 0: Completing All Crested Key Locations

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There are eight Crested Keys in Octopath Traveler 0, and you’ll need all of them if you want to unlock all eight legendary weapons. These weapons are very useful and will help you in the game’s final stages, so it’s important to collect these keys.

Although there are only eight keys, finding each one can be quite challenging in a game as large as Octopath Traveler 0, with its many NPCs and hidden dungeons.

Locations of All Crested Keys in Octopath Traveler 0:

Source	Location	Notes
Starting inventory	Auto-given	You can select Crested Key as a starting item, which makes things easier. It’s optional.
Viator	Valore (Tavern)	Viator will have a Crested Key when he joins your team. He seems ready to join once you’ve found a key in the world.
Mystery-Chasing Explorer	Sufraltajah	Approach this NPC with Entreat.
Black Market Merchant	Grandport	Found in the Grandport Markets. Use Entreat to obtain the key.
Young Antique Dealer	Victors Hollow	Use Purchase to get the item from this NPC.
Treasure Chest	Sweltering Cave	Located in Sweltering Cave, accessible through Berecain Pass.
Treasure Chest	Cyphlo Banks	Only accessible after early in the arc “Bestower of Power” and in the Cyphlo Banks area.
Shining Blue Item	Outersea (Isle East)	On this island, marked by a shiny spot that’s easy to notice.

The big question is, how do you get the eighth key if you didn’t pick it at the start? It’s likely a reward from a town upgrade, but the exact method isn’t confirmed. Many believe it could be tied to a specific town upgrade or quest.

How to unlock the Keys Together:

Once you have at least one key and recruit Viator, the Isle of Heroes will appear on your Outersea map. Sail there, watch the scene, and interact with the door to the tower. Take the teleporter upstairs, where you’ll face a boss fight. It’s the only boss you need to face, and it’s manageable at around level 65, though lower levels can do it with a good setup. Make sure you have a healer ready, as the boss hits hard.

After the fight, you’ll be able to start claiming the weapons that each key unlocks. Keep in mind, each key corresponds to a specific weapon, so if you’re missing a certain weapon, you might not have the right key yet.