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