In a dark void known as the Lightless Realm, a group of children meet and bond, but are then separated and returned to their own dimension. Years later, these children reunite to fight "Admonitions," monsters that originate from the same void, using robots known as "Vess." However, their efforts only slow the ever-encroaching and expanding Lightless Realm from infecting their world. Their lives take a drastic turn when a new foe appears in the form of a "Corpse," whose song is rumored to kill any who hear it within nine days. The "Corpse Song" is heard by the group, and with this, they each begin to pull away and become caught up in their own personal problems—ultimately threatening the fate of humanity.

Lin Yun, the sword slave of the Qingyun Sect in Tianshui Kingdom, after his rebirth, his aptitude with extremely poor comprehension became different. After a set of Tiger Fist, he directly broke through to the triple realm of martial arts that can become a disciple of an outside sect. However, even though he got rid of his identity as a sword slave and became an outer disciple, Lin Yun was still discriminated against by other disciples of the sect, all because of the unwritten rule of "one day a sword slave, a lifetime a sword slave"... The road to martial arts is full of hardships. How does Lin Yun constantly challenge himself, find opportunities for improvement, break the sect's grievances, rewrite the life of a sword slave, and step into the pinnacle of martial arts?

Three months have passed since the Demon King was defeated by a hero. Mankind rejoices over their victory, but dwellers of the demon world do not share the same sentiment. With the loss of their king, they must now hold a tournament to decide who will become his successor. Monitoring the competition is the hot-headed yet powerful Vamirio—one of the Four Heavenly Kings. Among all the participants, she is extremely distrustful of one: Helck, a human hero who claims to hate humanity. As much as she wants to get rid of him, it is impossible due to Helck's incredible strength and popularity. Amidst the competition, Vamirio discovers that humans have vanished from various towns. As a result of this puzzling turn of events, Vamirio grows desperate to reveal Helck's true intentions by carefully crafting a plan to make Helck lose. If she proves to be successful, she might uncover where his loyalty truly lies before the demon world is endangered.