In a world where clans waged a silent war, Ichinoya Kamisaru lived a peaceful life in his village, surrounded by his family. But that tranquility was reduced to ashes the day an enemy clan brutally wiped out the Kamisaru, slaughtering his parents and loved ones before his eyes. Gravely injured and deprived of his left arm, Ichinoya was the sole survivor, saved at the last moment by traveling merchants. Taken in at an orphanage, he met four other boys marked by the same tragedy: Jin and Sandaï Orikawa (inseparable twins), Kisame Ichimonji, and Shinku Wolfgang. They had all lost their families under similar circumstances, victims of the same invisible enemy. Bound by pain and a thirst for justice, they made a bloody promise: to become strong enough to hunt down and exterminate those who had shattered their lives.