This great Oni Daimyo is the personification of Rage, Bloodlust, and Slaughter, happily deceiving, killing, slaughtering, and feasting on anyone who will not kill in his name. While he has no physical form, back when he did, he appeared as a towering mass of muscles with countless arms, all wielding separate weapons.
In the lands of Minkai and Tian Xia, there exists a race of evil outsiders native to the material plane, known as the Oni. These evil creatures set forth to create destruction, chaos, and sate their greedy needs. Much like any race, the Oni are ruled over by a hierarchy of poweful beings, Demigods, and Gods.
Long ago, a great and powerful warrior named Xun Leiji was tasked by the Emperor to slay the Oni Demigod of Bloodlust, Rage, and Slaughter. This was done out of necessity, to attempt to stop the race of Oni from conquering and laying waste to massive stretches of civilization. When Xun Leiji set out, he was forced to battle through countless swathes of Oni in order to call down the Demigod, or Daimyo, in their tongue. This Daimyo was Ueru-Koto, who’s laugh resounded like thunder rolling over the mountains. Through Xun’s quest, he discovered that the purest black stone of a volcano, Obsidian, held special properties over the Oni, not merely cutting their flesh, but cutting their soul as well, and thus he crafted an exquisite blade from a single piece of obsidian rock. When Xun finally confronted Ueru-Koto, Ueru-Koto smiled with impossibly long teeth and attacked. The battle was said to have lasted for seventeen days, as the Oni Daimyo toyed with his assailant, allowing Xin to cut his body to ribbons before merely inhabiting another of Xin’s men. At the end of the battle, Xin stood atop a mountain of his own brethren, for whom he had personally slain one by one as Ueru-Koto jumped from soldier to soldier, and across from him stood Ueru-Koto, in his last man. Xin did not pause to assess the carnage he had caused until after he has decapitated this last man. As the head lay, still smiling an impossible smile atopp the bodies of the fallen, Ueru-Koto asked Xin to look around, for he had slaughtered all of his men in his pursuit, personifying that of Ueru-Koto’s beliefs in slaughter and bloodlust. Xin, seeing the destruction he had caused, quickly determined his fate, and fell to one knee, vowing allegiance to the severed head and the Oni Daimyo therein, asking to be an Avatar of Rage. Ueru-Koto was pleased, and accepted, pulling into the new Avatar in order to transform him. At this time, Xin used his last ounce of strength to plunge his sword deep into his own heart, hoping that the properties of the obsidian would prove useful. With his last dying act, after running his own heart through, he pushed Ueru-Koto into the hilt and broke it off from his chest, trapping the Oni inside.
For countless years, this hilt has been locked away behind runes and barriers, because the magic that sealed him within the hilt was weak, and could be broken by man’s will just as it was sealed. A collation of worshipers, clerics, and cultists formed to keep this great evil sealed, and they began periodically moving the Artifact from location to location using a series of uninformed couriers, so that no trace of the movement could be gathered. These same members also set forth to obliterate any mention of Ueru-Koto from history, hoping that the name would be lost to the ages.
Ueru-Koto himself is a great and powerful Demigod of Rage, Bloodlust, and Slaughter, who is deceptively intelligent. In his time, he led the Oni against everything they could kill, including each other.