Here is the full list of all 52 Ys: Memories of Celceta achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
Acquired all achievements.
Completed the Map of Celceta.
Opened every treasure chest.
Discovered every resource point.
Acquired at least one of every item.
Filled out all monster details in journal.
Filled out all material details in journal.
Mastered every skill.
Enhanced a weapon or armor to its limit.
Amassed one million gold.
Successfully used Flash Guard fifty times.
Successfully used Flash Move fifty times.
Achieved one thousand Aerial Combos.
Achieved five hundred Skill Finishes.
Defeated the ruler of the Great Forest.
Played extensively as Duren.
Played extensively as Karna.
Played extensively as Ozma.
Played extensively as Calilica.
Played extensively as Frieda.
Cleared the game on Nightmare difficulty.
Defeated a boss in Time Attack in thirty seconds or less.
Defeated a boss in Time Attack without taking damage.
Conquered Boss Rush.
Conquered Boss Rush without a single retry.
Restored all lost memories.
Completed the main story.
Overcame Gruda's trial.
Successfully completed every quest.
Endured all of Zara's tickle sessions.
Purchased every piece of info from Mouse.
Opened the door to the Temple of the Sun.
Acquired both halves of the Mask of the Moon.
Cleared all obstructed paths.
Found all of Mishy's hiding spots.
Arrived in the ruined capital, Elduke.
Walked an extraordinary total distance.
Befriended all animals.
Located the underground village of Danan.
Proved your skill as a merchant.
Reunited with Eldeel at the Tower of Providence.
Defeated two thousand enemies.
Successfully arrived in the Primeval Lands.
Achieved five hundred Excellent Kills.
Defeated a rare golden foe.
Resolved the polluted river dilemma.
Defeated Duren in one-on-one combat.
Solved the mystery of the missing villagers.
Discovered a settlement in the Great Forest.
Played extensively as Adol.
Successfully rescued the trapped miners.
Began your adventure in Celceta.