Eleven years have passed since the fierce war between humans and demons ended in a ceasefire... and now, an era of “human-demon coexistence” has begun. During the war, a young man named Eita was the wielder of the “Shiki-no-To,” a sword developed as a weapon of mass destruction. Now, he scrapes by doing day labor while searching for his long-lost sister, Kanna. But one day, when he saves a familiar young demon named David from being attacked by demon soldiers, Eita is once again branded a demon slayer—and becomes a wanted man. Thus begins the wandering journey of Eita and the little demon, hunted and on the run!