During a time of great need for humanity, when the gods had gone silent, they turned to a demon as their last resort. This supposed savior, armed with the bloodthirsty sword Zsoltgewinn, not only failed to protect its summoners but also turned out to be a threat. Although the sword was buried, the Shoshidai found it along with other cursed relics. Unfortunately, the sword proved uncontrollable and poisoned its administrator, Takuma Miura, causing him to flee with it. Gai Ogata's life crumbles when his family is killed by Shiryu, another demonic sword. His father is murdered and his mother takes her own life, leaving Gai to be born clutching the wicked blade in the forest. Amon the blacksmith discovers the orphan and is fascinated by the sinister weapon Gai was born with. Although Amon loses an arm in an accident, he creates a startling replacement: a reworked Shiryu. Now Gai must struggle to control his cursed arm, unaware of the bloody trail left by Zsoltgewinn.