Cardia

"This is the «Demon Lord of the Heart». For others who were called Demon Lords go here."

《Demon Lord of the Heart, Cardia》 is the Demon Lord sealed in 《The End》 in the Kingdom of Greenwood.

Appearance
Cardia appears to have a large grotesque figure with numerous black tentacles, but its actual body is still sealed away and its form is merely an illusion.

Background
When God split apart the Originator Demon Lord, Cardia was sealed in the Kingdom of Greenwood and the royal family was ordered to guard the seal.