In a kingdom once ruled by humans, demons have risen to power, enslaving humanity after a brutal war. Amid this chaos, a fiery young boy named Kajin fights to survive, hunted relentlessly by demon soldiers. Kajin has a dark twisted story, his goal to claim the throne of the Demon Kingdom and rule over the humans and the demons together seems hard but not impossible. Will he achieve his dream? Will he learn about the truth about the war?