Origin
According to Naho's blog, it is stated that this ritual is centered around a local folk legend from Tenjin.
There, a young elementary schoolgirl named Sachiko went missing around 30 years ago.
Even though she died within its grounds, it is said that her spirit still wander the Earth, but she has been given powers to grant wishes and ease worries to others.
This ritual is intended to induce communion with Sachiko's spirit and, if performed correctly, Sachiko will pass through and grant you her blessing; Those involved in the spell will be bound together as true friends for eternity.
However, if the ritual is not performed exactly as specified, Sachiko may be angered which can only lead to trouble.
Instructions
In order to perform the ritual, at least two to ten participants are needed.
With the paper Sachiko doll in hand, everyone needs to gather around in a circle and each individual must grip firmly onto the proxy doll.
Then they must invoke Sachiko by chanting the phrase in your head, "Sachiko, we beg of you" (「サチコさん(に)お願いします」 "Sachiko-san (ni) onegaishimasu"?), one time for each participant present plus once more for Sachiko herself.
After chanting, everyone holding onto the paper doll pulls it apart, leaving each person with a paper doll scrap (サチコさんの切れ端 Sachiko-san no kirehashi?).
It is suggested to keep this paper scrap on your person, such as putting it inside your student ID holder or wallet.
Succeeding in the ritual causes nothing to occur.
However, performing the charm incorrectly either by repeating the phrase too many times or too few, invokes the wrath of Sachiko.
It causes those involved to be dragged into Heavenly Host Elementary School, not to mention this ritual alone is the one responsible for sending countless souls to their inevitable demise.
Once brought into the accursed school, the scrap papers from the Sachiko charm are critical for escaping Heavenly Host.
The remaining participants must join their paper doll scraps together and then perform the ritual once more, this time done correctly.
Afterward, those involved will finally be able to return back to their own world.
Furthermore, losing these paper scraps means the individual can never return home.