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