Here is the full list of all 45 AI: The Somnium Files achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Obtained all other trophies.
Collected all the "Dream Album" files.
Found all hidden items in Somnium.
Found 6 hidden items in Somnium.
Checked absolutely everything in Boss's office.
Confronted So with the evidence with no mistakes.
Confronted Iris with the evidence with no mistakes.
Confronted Ota with the evidence with no mistakes.
Admired the Sagan's stereo equipment.
Discovered the marriage of the yakuza and the nurse.
Found 1 hidden item in Somnium.
Finished the final investigation.
Kept your cool and did not shoot Saito.
Collected all the "Persons" files.
Day 6: Wednesday - Cleared Saito's Somnium.
Finished Annihilation Route investigation.
Day 5: Tuesday - Cleared Boss's Somnium.
Cleared the shooting event at the Sagan residence with no misses.
Day 5: Tuesday - Cleared Hitomi's Somnium.
Confronted Hitomi with the evidence with no mistakes.
Saw This Man twice in Somnium.
Finished Mizuki's investigation.
Day 6: Wednesday - Cleared Date's Somnium.
Almost got cursed by Adorabbit in Somnium.
Cleared the shooting event at the Sejima residence with no misses.
Asked out the receptionist to Atami.
Finished Ota's investigation.
Day 5: Tuesday - Cleared Mayumi's Somnium.
Saw three autographs of crazy customers in Somnium.
Had Aiba wear the basket and the pot in Somnium.
Day 4: Monday - Cleared Ota's Somnium.
Day 4: Monday - Cleared #89's Somnium.
Collected 100 "Appendix" files.
Day 3: Sunday - Cleared Iris's Somnium.
Cleared the shooting event at the Kumakura office with no misses.
Enjoyed a fulfilling chat with Kagami.
Finished Iris's investigation.
Day 5: Tuesday - Cleared Iris's Somnium.
Cleared the shooting event at the Warehouse District with no misses.
Day 4: Monday - Cleared Iris's Somnium.
Cleared the shooting event at Golden Yokocho with no misses.
Day 3: Sunday - Cleared So's Somnium.
X-rayed the Mermaid.
Day 2: Saturday - Cleared Mizuki's Somnium.
Day 1: Friday - Cleared Date's Somnium.