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