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