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