The Blue Moon Abyss (ブルームーンアビス Burūmūn'abisu ) is a cave which is under Luna Nova Academy whose entrance only opens on the nights of blue moon. There resides the spirit of the witch Woodward who is said to be able to answer any question about the past, present or future to those who can appease it.
The Blue Moon Abyss is a great subterranean cave the which can only be entered by the entrance underneath the chapel at the base of Luna Nova Tower. The entrance apparently only can be opened in the nights of blue moon when the light of this illuminates the Shiny Rod. It is composed of several tunnels of blue stone.