Wave of Raual

The Wave of Raual (ラウアールの波), also known as the Otherworldly Moon (異界の月), the Another World accumulation of Harmful Frequencies (害周波), is a devastating wave that occurs when a civilisation is on the verge of collapse.

Trivia

 * 'Raual' might be an alternative spelling of the French 'Rahouart', a demon mentioned in a book by Renaissance author Durzel, the name of a character in.