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