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