Toilet-Bound Hanako-Kun, Volume 2 (by AidaIro)

Nene Yashiro has made a pact with “Hanako-san of the Toilet,” aka Hanako-kun, to hold off the curse that has been placed on her. In exchange, she has to help him resolve the problems caused by the school’s supernaturals―starting with rescuing her friend Aoi from the clutches of the Misaki Stairs, one of the infamous Seven Mysteries. Can they reach the innermost depths of the Stairs before time runs out? And if they do, what dangers and secrets await them there...?