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.
Saw three autographs of crazy customers in Somnium.
Discovered the marriage of the yakuza and the nurse.
Saw This Man twice in Somnium.
X-rayed the Mermaid.
Enjoyed a fulfilling chat with Kagami.
Admired the Sagan's stereo equipment.
Checked absolutely everything in Boss's office.
Asked out the receptionist to Atami.
Collected all the "Dream Album" files.
Found all hidden items in Somnium.
Had Aiba wear the basket and the pot in Somnium.
Almost got cursed by Adorabbit in Somnium.
Confronted So with the evidence with no mistakes.
Confronted Ota with the evidence with no mistakes.
Confronted Iris with the evidence with no mistakes.
Cleared the shooting event at the Sejima residence with no misses.
Found 6 hidden items 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.
Finished Iris's investigation.
Day 5: Tuesday - Cleared Iris's Somnium.
Cleared the shooting event at the Warehouse District with no misses.
Collected 100 "Appendix" files.
Day 4: Monday - Cleared Iris's Somnium.
Cleared the shooting event at Golden Yokocho with no misses.
Day 3: Sunday - Cleared So's Somnium.
Finished Mizuki's investigation.
Day 6: Wednesday - Cleared Date's Somnium.
Finished Ota's investigation.
Day 5: Tuesday - Cleared Mayumi's Somnium.
Day 4: Monday - Cleared Ota's Somnium.
Day 4: Monday - Cleared #89's Somnium.
Day 3: Sunday - Cleared Iris's Somnium.
Cleared the shooting event at the Kumakura office with no misses.
Day 2: Saturday - Cleared Mizuki's Somnium.
Day 1: Friday - Cleared Date's Somnium.
Found 1 hidden item in Somnium.