Nene Is A No no

Hanako, a ghost that will grant you any wish with an unknown price. Hanako is friends with a girl, Nene Yashiro.

To summon Hanako:
Go to the girls bathroom on the third floor
Walk up to the third (last) stall
knock three times
and say:
"Hanako, Hanako, Hanako,"
"are you present?"
and wait for Hanako's response