Kaisen Cavern

Kaisen Cavern (芥沾洞, Kaisendou), known also as the Poppydew Aerie , is the residence of a hisen who is one of the few friends of Riyou, the mistress of Suibi Cavern. Kaisen Cavern is located on Mount Ga (臥山, Gazan).

The mistress of Kaisen Cavern is the mother of a previous ruler of the kingdom of Kei from many generations earlier. Shortly after the enthronement of Youko Nakajima, Riyou mentions how she encountered the new ruler of Kei when she went to visit the mistress of Kaisen Cavern.