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