Here is the full list of all 21 Ys SEVEN achievements.
Complete the game on any difficulty.
Complete the game on Nightmare difficulty.
Obtain all other achievements.
Synthesize all Dragon Stone weapons.
Learn every skill.
Unlock all bestiary entries for all non-boss, non-titano foes.
Raise all of any one character's skills to max level.
Synthesize each Spirit Elixir at least once.
Conquer the Moon Dragon, Ze-Kalion.
Conquer the Sea Dragon, O-Balon.
Buy every item from the Zanzibar Firm.
Conquer the Flame Dragon, Angue-Barl.
Find all the missing pikkards.
Defeat all titanos.
Conquer the Earth Dragon, Rada-Manj.
Conquer the Wind Dragon, Mu-Anti.
Survive against a beast intended specifically to kill you.
Defeat Geis in one-on-one combat.
Escort Tia back to Altago City completely unscathed, and without using any healing items.
Die by walking over thorns.
Die by drowning.