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