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