The Mad King is an unnamed monarch who inhabits the forest that lies between the Bosse Kingdom and the Underworld.
Bojji briefly encountered this king while lost in the forest.
The Mad King is a very tall old man with grey eyes, an emaciated face, unkempt grey hair, and a large grey moustache. He wears a yellow fur tunic and darker-yellow fur boots, both of which appear to be made out of pelts. His eyes are slightly askew, giving him an air of madness.
The only thing that identifies him as a king is the solid gold crown upon his head.
(Source: Ousama Ranking Wiki)