Dark Gathering, Vol. 7 (manga)

Before Keitaro, Yayoi, and Eiko can set off on their next haunted site expedition, they need to acquire another of the sealed graduates—a vengeful courtesan looking to escape from Yayoi’s control. However, things turn even more dangerous when Keitaro is drawn into the spirit world, forcing him to contend with the horrors of a haunted love hotel’s bloody history all on his own.