Book 4: Story Art 1
The first three images you've already seen as I've posted them in the author's notes prematurely before the post they were originally in.
But the last three you haven't seen. And it has the full names and Titles of the Demon Lords in it with their pictures.
Scarlet Art Asger de Archeron:
Arkaz Luna Val de Archeron, the Beast of the Apocalypse, the Blood Immortal, the Sovereign of Blood, the Demon King, and Scarlet's Grandfather:
Lucius Tor de Blackheart, the Lord of Death and The Reaper: