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