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.
Checked absolutely everything in Boss's office.
Had Aiba wear the basket and the pot in Somnium.
Saw This Man twice in Somnium.
Enjoyed a fulfilling chat with Kagami.
Admired the Sagan's stereo equipment.
Found all hidden items in Somnium.
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.
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.
Found 6 hidden items in 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.
Confronted So with the evidence with no mistakes.
X-rayed the Mermaid.
Day 4: Monday - Cleared #89's Somnium.
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.
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.
Day 4: Monday - Cleared Ota's Somnium.
Day 3: Sunday - Cleared Iris's Somnium.
Confronted Iris with the evidence with no mistakes.
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.