Here is the full list of all 21 Ys SEVEN achievements.
Complete the game on Nightmare difficulty.
Obtain all other achievements.
Synthesize all Dragon Stone weapons.
Unlock all bestiary entries for all non-boss, non-titano foes.
Learn every skill.
Buy every item from the Zanzibar Firm.
Raise all of any one character's skills to max level.
Synthesize each Spirit Elixir at least once.
Complete the game on any difficulty.
Conquer the Moon Dragon, Ze-Kalion.
Find all the missing pikkards.
Conquer the Sea Dragon, O-Balon.
Die by walking over thorns.
Defeat all titanos.
Conquer the Wind Dragon, Mu-Anti.
Conquer the Flame Dragon, Angue-Barl.
Conquer the Earth Dragon, Rada-Manj.
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 drowning.