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