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