Here is the full list of all 33 OCTOPATH TRAVELER II achievements.
Brought along four townspeople at once.
Completed Castti and Ochette's Crossed Path.
Completed Temenos and Throné's Crossed Path.
Completed Agnea and Hikari's Crossed Path.
Completed Agnea's story.
Completed Osvald and Partitio's Crossed Path.
Completed Osvald's story.
Completed Partitio's story.
Completed Temenos's story.
Completed Ochette's story.
Completed Hikari's story.
Completed Castti's story.
Dealt 9,999 or more damage.
Completed Throné's story.
Learned a job's divine skill.
Gathered all eight travelers.
Gleaned information from 100 townspeople.
Rode the ferry to a new land.
Embarked on a journey.
Learned a skill for the first time.
Acted at maximum boost for the first time.
Broke an enemy for the first time in battle.
Unlocked all achievements.
Returned dawn to the world.
Approached the end of your journey.
Learned all EX skills.
Learned all secondary jobs.
Traveled to every location on the map.
Defeated the netherworldly threat.
Finished all side stories.
Obtained all records.
Obtained all battle-tested equipment.
Soothed or knocked 100 townspeople unconscious.