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