In Brahmanda Purana, http://www.gloriousindia.com/scriptures/puranas/brahmananda_purana/preaching_of_bruhaspati.html
Bruhaspati replied "In the distant past, Diti, the second wife of Kashyapa gave birth to a son by name Danu and a daughter named Rupavati. Danu is the predecessor of the race of Danavas (demons). Rupavati was married to Brahma (the Creator).
I am confused about this, Is Danu the first demon? and before him there is no demons?
please I need an answer to finish my research.