Aeges Code

He is one of the Four Evil Kings, known as the Netherworld King. He is a great demon who competed with Demon King "Anos" and the Blaze Death King "Eldmed" during the Mythical Age.
Like many of the prominent demons from the Mythical Age, Aeges moved away from Dilhade and ended up in Aharthern, where he began attending the Spirit School alongside the other Evil Kings.

He is prudent and often serious but can be pretty laid back and relaxed during peaceful times. He cares deeply for those he considers close to him. He is also a man of his word, who detests trickery and manipulation.
The true nature of Aeges Code's source is blood. The more Aeges approaches his destruction, the more blood his source generates and the more powerful his spears become. His blood contains powerful magic that works in conjunction with his spear.

(Source: Maou Gakuin Wiki)