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