OCTOPATH TRAVELER

For this achievement, you must complete every side-quest in the game. These are marked by orange speech bubbles over NPCs in the world. Generally, they are quite straightforward, though a few do have two methods of solving them. A full list of every side-quest with their solutions can be found in the Neoseeker walkthrough I linked in the Road Map. None are missable, and the rewards are generally helpful, so try to complete them as you go. Your last one will unlock after beating the game, and is for defeating the superboss of the post-game dungeon.