(Unique game aspects not part of story canon)
Belial (ベリアル beriaru ) was a bioweapon engineered by Vasilisk Corporation. A simulated version of Belial was created for the Vasilisk computer system to test out its combat effectiveness without real-world testing. It was named after the King of Hell in demonology.
Belial is one of the three standard "Clan Creatures", who represent an online team and which must be defeated in online battles.