Diablo

Originally known as the Primordial Black 'Nova,' Diablo stands as one of the seven ancient demon lords of the netherworld. Captivated by the boundless potential he witnessed in Rimuru, he willingly answered the summoning call during the Farmus Kingdom campaign and, upon receiving his name, transformed into a fiercely devoted personal butler. In everyday affairs, he carries himself with aristocratic grace and exceptional competence; yet when confronting adversaries, that elegance gives way to an overwhelming, demon-lord-class ferocity. He remains Rimuru's most trusted and formidable confidant.