It’s the year 952 on Cartland Calendar, Demon King Krotin and four demon lords lead the demon army to attack the Cartland Kingdom in the northern part of the central continent. When the war is at a stalemate, a brave man Jad Dove fights into the Demon Capital alone and finally defeats the four demon lords and kills Demon King Krotin. Jad thought this would be the end of the war between humans and demons, but troubles keep coming one after another, and he also discovers the secrets of the Cartland Kingdom.
 
(Source: Made By Bilibili)

After defeating the Demon King, our Hero saves the princess and rides off into the horizon to start a new life... In his dreams... Little did he know that unemployment and mediocrity awaited him. Comic Fantasy at its best. (Source: Lezhin US) 
Note: Chapter count includes a prologue.

Krodin