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