The ritual should be done at New Moon.
Prepare three rooms (or if that is impossible, two rooms will suffice), adjacent to each other. Preferably these rooms should be arranged in a way that they draw the shape “L” when viewed from above.
The room in which group gather should be completely dark; the next room likewise. The third room should contain a hundred Andon (a lantern with a wooden flame and paper shade) and a mirror on a table.
The paper which the Andon is made of should be blue in color. All participants should also be attired in blue, and all should enter the first room without carrying swords. Put away any other weapons and such dangerous objects from the room (although there were some who would adorn the room with a sword, to ward off evil)
When a story is told, the storyteller has to grope his way in the dark to the third room where he is to put out one andon, look himself in the mirror, and return to the first room once more. The group is allowed to continue story-telling while the previous storyteller is away. The stories here do not have to be only about ghosts or monsters; they could be stories of enigma or a curse. When all the stories are told and the true darkness descends, something supernatural will happen.
In reality when they used to perform such ritual, they often stopped at 99th story and waited until the daybreak. It was because the true purpose of the ritual was to test one’s courage, and they did not want the risk of actually summoning a supernatural being.