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