Belial is a "Prince" living in The Darkness.
The Prophecies of Ishtar hint that he assisted the Grigori in exchange for the souls of everyone who dies in the Tower. However, the Grigori were initially unaware that humans who died ended up in The Darkness, at least according to the Freemen's Notes.
Chapter 07: The Cry of ArmarosEdit
Chapter 08: Belial's TemptationEdit
After his actions during the previous chapter, Belial is "sleeping".
When Armaros completely destroys Enoch's Dark Armor, however, it angers Belial who unleashes the vileness on them. Lucifel intervenes by rescuing Enoch and Nana, but leaves Armaros to be consumed, shouting with despair.
Chapter 11: Semyaza's DreamEdit
- When Armaros stumbled upon a giant spiked ball, it was noted that Prince Belial was sleeping. This implies Belial is either the ball itself or an entity inside it.