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