After you choose Q-Team's Triangle fragment, you must escape the study.
Seek a Way Out
Check the right-hand drawer of the desk to find a key with a Human symbol on it.
Use the Human shape key on the safe that has the Human mark on it.
Inside the safe, you find Part D, the Star mark key, a handgun, and a Birdman card, which has four letters on it.
Use the Star mark key on the safe that has a Star mark on it. Inside, you find Part C, the Moon card, and Note 1.
Touch the stairs to go up. Look to the left to find a note on the floor, called the Polovtsian Secret.
The upstairs safe has a moon symbol on it, with a Polovtsian Doll on it. Check the note that you got upstairs to figure out the meaning of the doll.
The Moon card that you found earlier says NIL on it, so enter NIL in the Moon safe, then touch the handle that says OPEN. You get Part E, a crossbow, and the Sun card.
Go back downstairs. Find the safe with the Sun mark on it. It has a Polovtsian Doll on it, so check the note in your Files if you don't remember what the doll signifies.
Based on the Sun card that you got, and the Polovtsian Doll on the Sun safe, you should enter EXIST in the Sun safe, then touch the handle to open it. You get Part F.
There is also a lever in the Sun safe. Touch it to power up the orange chair.
Touch the orange chair to sit in it. Earlier you found Note 1 in this room, which had S-02-16 on it. Enter that into the orange chair's console.
You get Polovtsian Secret 2, which shows the significance of more poses.
The Bird card has four letters on it, and there are four Polovtsian Dolls on the desk. What do the four letters become if you change them based on those four dolls' poses?
The answer is MIND. Touch the Cryptex (the item on the chair with the Birdman symbol on it) and enter MIND.
You get a note that says Bullet for C-Team, Arrow for Q-team, Acid for D-team (but the D-team part is crossed out).
Equip the handgun and go to the fireplace. If you are not sure which pictures correspond to which characters, open the menu and choose STATUS to see the name of each character beside each portrait. With the handgun equipped, shoot the pictures of Carlos, Akane (the one with cat ears), and Junpei (the one that looks kind of like a zombie).
Then equip the crossbow and shoot the pictures of Q-Team. (There is no portrait for Q in the STATUS menu, but you can just use the process of elimination to figure out which picture is Q's.)
After you shoot the correct pictures with the correct weapons, check the box that opens and you get a grenade launcher.
Equip the grenade launcher and use it on the cracked glass door. Check inside where the glass door was. There are three dolls in the same pose. You also get Part A, and Note 3. Which says J-05-03.
Use the orange chair. The Polovtsian Dolls behind the glass all said to move 7 down, so use that on the information in Note 3. This gives you the correct code: Q-12-10. Enter that code in the orange chair.
You get a blueprint that shows how to assemble the parts. In your inventory, combine A+B to create part AB, then combine C+D to create part CD, then combine E+F to create part EF. After that, combine AB+CD to create Part ABCD. Finally, combine part ABCD with part EF. This creates a key.
Use the new key in the keyhole of the large safe behind the desk. This ends the escape puzzle.
You will be prompted to enter a character's name. You could enter ERIC or MIRA, but as you can see from the flow chart, there are two other choices.