In the Glow City, where steam and gears roar, magic is considered taboo, and mechanical civilization reigns supreme. The young boy Xiao Mo was originally a genius student at Huiguang Mechanical College, but he was framed by his best friend during the graduation examination, accusing him of secretly practicing the forbidden "Devil Contract Technique". In front of everyone, the magic power in his body suddenly lost control, and his eyes turned scarlet - only then did he realize that he was not a human at all, but the reincarnation of the ancient demon emperor.
Xiao Mo, who was sentenced to death row by the Inquisition, awakened the memory of his past life and the golden finger of the [Forge of All Demons] when he was about to die: he could swallow all steam machinery and monster energy and smelt it into the power to strengthen himself. When he broke out of prison, Glow City classified him as a "demon disaster" and sent out the strongest mechanical demon hunting army to encircle and suppress him.
Xiao Mo didn't want to kill innocent people indiscriminately, he just wanted to find out the truth about his life experience. However, every time he took a step back, the enemy took another step forward. The hypocritical Mechanicus Church, the ambitious Steam Nobility, the real devil lurking in the shadows - everyone wants to use or destroy him. When justice no longer protects kindness, and when order becomes a tool of oppression, Xiao Mo finally understands: Since he is not allowed in the world, he will rule this cold steam city in the name of the devil!
