Three-Room Ritual

This page contains spoilers. Read at your own peril!

The Three-Room Ritual is one of the rituals within the Golden Envelopes. This ritual and its consequences are the plot of the prologue of Paper Lily, Project Kat. It spirits the user away to a hallway of doors.

Instructions

You must play alone.
Requirements:
- 3 dark, adjacent rooms.
- 12 candles.
- A lighter or matches.
- A rune.
- A tuft of human hair.
- White chalk or white paint.
Preparations:
Start after the sun has set.
All 3 rooms must be pitch black; turn of all the lights, draw the curtains, and close the doors.
Using chalk or paint, draw a path going through all 3 rooms. This path will serve to connect your current location to your destination.
In the middle room, place 6 candles in each side of the drawn path parallel to it.
Instructions:
Light each of the candles and let them burn for at least 5 minutes. From this point you can no longer abort the ritual.
After 5 minutes has passed, burn the tuft of hair on one of the candles.
Proceed to blow out all the candles one by one.
When the last candle is put out, quickly close your eyes and count to 100.
Open your eyes.
To Remember:
You must always close the door behind you. Leaving it open may attract unwanted attention.
Do NOT let the rune out of your possession. It is your only protection.
DO NOT bring any weapons with you. If you arm yourself so will they.
Should anything be heard or felt while you count to 100, it must be ignored.
Do NOT open your eyes.
Do NOT turn on the lights. 
It is normal to feel like you are not alone. You won't be.

Of note is that the point of no return for this ritual seems instead to be once the chalk/paint is placed and the rooms are dark (in game you can tell once you have reached the point of no return by the disappearance of the girls. However from this point despite escape being impossible, it is not the the demon which ultimately kills Kat it is instead the lack of food/water as she dies in the infinite staircase.