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