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