Here is the full list of all 48 Persona 3 Reload achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Watched the good ending.
Sealed Nyx.
Maxed out all Social Links.
Invited Elizabeth to your room.
Fused Messiah.
Unlocked all Social Links.
Defeated the Reaper.
Awakened all teammates' ultimate Personas.
Unlocked a teammate's Combat Characteristic.
Defeated the Hanged Man.
Encountered a Dark Zone in Tartarus.
Nurtured a romance.
Defeated Fortune and Strength.
Maxed out all Social Stats.
Discovered and conquered 10 Monad doors.
Earned over a total of 50,000 yen from part-time jobs.
Defeated the Hermit.
Dealt over 999 damage in a single attack (All-Out Attacks excluded).
Used all teammates' Theurgy.
Acquired every Twilight Fragment in town.
Defeated the Chariot and Justice.
Nursed a cat back to full health.
Maxed out one Social Stat.
Unlocked access to the remaining Major Arcana.
Aced an exam.
Maxed out one Social Link.
Defeated the Hierophant and the Lovers.
Harvested a crop that you grew with a teammate.
Accepted an invitation to hang out five times.
Rescued a missing person.
Spent an evening in the dorm with a teammate.
Initiated 50 Chance Encounters.
Used a total of 50 Twilight Fragments.
Obtained 10 Major Arcana during Shuffle Time.
Defeated the Empress and Emperor.
Obtained an item from a Persona Conception.
Ordered from a secret menu at the Iwatodai strip mall at night.
Performed a fusion with three or more Personas.
Defeated a rare, golden enemy.
Triggered a skill change during fusion.
Performed 50 All-Out Attacks.
Obtained 10 Personas during Shuffle Time.
Opened 50 treasure chests.
Defeated the Priestess.
Performed a Dyad Fusion.
Performed a Shift.
Joined the Specialized Extracurricular Execution Squad.
Obtained Orpheus.