Sainokawahara Dorm

Sainokawahara Dorm is an old girls' dorm in the Nerima area. The dorm is actually very run down and has been abandoned for a long time, but the ghost of the Headmisstress tricks Happosai into thinking it is new so he will steal her underwear. Only after her underwear is stolen can her spirit move on into the next realm. It isn't clear what happened to the dorm after the events.

Before being abandoned, the students frequently had their panties stolen (although it doesn't explicitly state that it was by Happosai), but the headmistress's underwear remained intact. When she died, she used the dorm to lure Happosai into stealing her panties.