Here is the full list of all 21 Etrian Odyssey II HD achievements.
Reached the Fifth Stratum.
Defeated a boss in a single turn.
Dealt 1,000 damage with a single hit.
Reached the Fourth Stratum.
Encountered an enemy through mining ore, gathering plants, or chopping wood.
Reached the Third Stratum.
Unlocked the Beast class.
Reached the Second Stratum.
Reached the First Stratum.
Obtained all other achievements.
Reached the Sixth Stratum.
Defeated the boss of the Sixth Stratum on Expert difficulty.
Defeated the Overlord.
Defeated the Ur-Child.
Retired an adventurer.
Let an adventurer rest.
Obtained more than 250,000 Ental.
Completed the quest "The beautiful Queen".
Defeated the Wyrm.
Defeated the Drake.
Defeated the Dragon.