The protagonist, Chu Xinghe, was an obscure menial disciple of Qingyun Sect in the Tianyuan Realm. After rescuing his junior sister, he was falsely accused of murdering his master, had his dantian crippled, and fell to the very bottom of fortune. On the verge of death, he unexpectedly activated the Myriad Realms Devouring System, setting out on a bloody and unpredictable path of cultivation.
The System gave him the heaven-defying ability to seize cultivation methods from different worlds, but this power carried hidden dangers. Every new force he devoured planted a seed in his heart that eroded his mind. As he fled and grew stronger, Chu Xinghe met key figures such as You Luo, princess of the Netherworld, and Li Yue, empress of the Mechanical Clan. He swore brotherhood with the vicious beast king Fentian and became entangled in an inextricable relationship with his junior sister Su Wanqing.
Forced to absorb the Netherworld Soulfire and become a half-human, half-spirit monster, he was hunted by both righteous and demonic factions. He fled from world to world, devouring powerful forces such as the Rune Energy Core and Undying True Blood, and climbed step by step toward the summit. But the System's dark side gradually emerged. His emotions were tampered with and locked away; his brothers betrayed him, and his Dao companion turned against him. The seeker of justice became the reviled Ancestor of All Demons.
At last, he learned that he was merely a vessel for the karma of all worlds, cultivated by the will of chaos and used as a pawn by the lofty Celestial Venerables. Driven to despair, Chu Xinghe descended into darkness completely and took extreme measures to exact revenge on all worlds. The story ends amid the spectacular collapse of the universe, but a hidden thread remains: Chu Xinghe's demonic thoughts become a new System, waiting for its next Host. It leaves readers with endless wonder and sorrow, presenting a world that is both cruel and awe-inspiring
