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.
Confronted So with the evidence with no mistakes.
Finished the final investigation.
Discovered the marriage of the yakuza and the nurse.
Kept your cool and did not shoot Saito.
Collected all the "Persons" files.
Found all hidden items in Somnium.
Collected all the "Dream Album" 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 4: Monday - Cleared #89's Somnium.
Had Aiba wear the basket and the pot in Somnium.
Day 5: Tuesday - Cleared Hitomi's Somnium.
Confronted Hitomi with the evidence with no mistakes.
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.
Checked absolutely everything in Boss's office.
Finished Ota's investigation.
Day 5: Tuesday - Cleared Mayumi's Somnium.
Saw three autographs of crazy customers in Somnium.
Confronted Ota with the evidence with no mistakes.
Saw This Man twice in Somnium.
Cleared the shooting event at the Warehouse District with no misses.
Cleared the shooting event at Golden Yokocho with no misses.
Cleared the shooting event at the Kumakura office with no misses.
Day 4: Monday - Cleared Ota's Somnium.
Collected 100 "Appendix" files.
Found 6 hidden items in Somnium.
Day 3: Sunday - Cleared Iris's Somnium.
Confronted Iris with the evidence with no mistakes.
Enjoyed a fulfilling chat with Kagami.
Finished Iris's investigation.
Day 5: Tuesday - Cleared Iris's Somnium.
Day 4: Monday - Cleared Iris's Somnium.
Day 3: Sunday - Cleared So's Somnium.
X-rayed the Mermaid.
Day 2: Saturday - Cleared Mizuki's Somnium.
Admired the Sagan's stereo equipment.
Day 1: Friday - Cleared Date's Somnium.
Found 1 hidden item in Somnium.