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.
Sealed Nyx.
Watched the good ending.
Maxed out all Social Links.
Unlocked all Social Links.
Fused Messiah.
Defeated the Reaper.
Awakened all teammates' ultimate Personas.
Earned over a total of 50,000 yen from part-time jobs.
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.
Dealt over 999 damage in a single attack (All-Out Attacks excluded).
Maxed out all Social Stats.
Used all teammates' Theurgy.
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.
Defeated the Hierophant and the Lovers.
Rescued a missing person.
Maxed out one Social Stat.
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.
Performed a fusion with three or more Personas.
Defeated the Empress and Emperor.
Acquired every Twilight Fragment in town.
Obtained an item from a Persona Conception.
Ordered from a secret menu at the Iwatodai strip mall at night.
Triggered a skill change during fusion.
Performed 50 All-Out Attacks.
Opened 50 treasure chests.
Defeated the Priestess.
Obtained 10 Personas during Shuffle Time.
Initiated 50 Chance Encounters.
Performed a Dyad Fusion.
Performed a Shift.
Defeated a rare, golden enemy.
Joined the Specialized Extracurricular Execution Squad.
Obtained Orpheus.