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