User blog comment:B214/Question and Answers 3/@comment-24098614-20140615084744/@comment-1359322-20140615093430

If it was before the Brave Saint was created, then most likely, but now that the Brave Saint is already created, they are already on their way to regain their strength. Plus as Azazel mentioned in Volume 4"

"“They won’t attack here again. It was a rare chance for an assassination on the leaders of the three great powers at the conference, but that also failed. Their current opponents are Heaven and the Underworld. In the Underworld, all the Fallen Angels under my orders have joined together with the Devils. The Underworld won’t fall so easily. The Seraph guys in Heaven also wouldn’t remain silent. Also, there are the free-loading strong sacred beasts in heaven and demonic beasts as well.”"

The Heavens might actually be more powerful than the Underworld's forces of Fallen Angels and Devils.