Zi Yu is a tall, slender man with a muscular build and long, white hair that covers about half of his face allowing his eyes to be unseen. He wears a white, no-sleeve shirt with a column of stitches that run down the middle of it. Below, he wears a red sash and a white skirt that covers his brown pants underneath; this ensemble is covered by a cloak that only covers his back and his upper body. On his wrists, he wears a band of white fiber with red strings that surrounds it and this design applies to the bands on his ankle that cover the top of his black shoes.
Zi Yu is a reticent and composed man, as well as silent and steadfast in his beliefs. At one point, he loved his brother's soon to be wife, Da Ji, but knew his aloof personality would never allow them to be together so he gracefully let his brother marry her by them finding their love naturally; he wanted the two of them to be happy together. Zi Yu is filled with a desire in his heart to find a purpose in his life as he did not truly feel fulfilled unless he was swinging his sword. This led him to wanting to focus solely on improving his swordsmanship and trying to fight stronger people in order to satisfy his passion. This is the reason he abandoned the throne to Zi Shou in order to become a wanderer and fight many powerful opponents, as the throne felt constricting to him; he has an affinity for being free.
He also holds a strong sense of justice and is determined to protect the weak against anyone. This is why he fought against the gods' rule, as he explained to Zhen Chan and Tian. Due to this trait, he is relentless and unwavering in battles and will kill an opponent without haste, if he feels he has to. He even went as far as to defend the natives against Wu Geng and the Dark Ones (although he noticed there was something wrong with Wu
Geng), despite helping them to fight against the gods.
Zi Yu also prefers to fight his battles using his own powers and hates relying on others powers, as shown when he didn't want Qiong Xiong Jie's soul power. He also hated Qiong Xiong Jie, but he still gave Jie his respect, saying that the latter won his dignity, which he feels it's something that the weak, who easily submit to the gods, will never have .
Zi Yu is an exceptionally strong fighter, being the strongest human ever lived as stated in the story. He is known by soldiers and gods alike for being the strongest swordsman and a formidable opponent. Before Zi Shou rebelled against the gods, Zi Yu was said to have killed a god, which made Shi Xing acknowledge his strength in their first clash . He has shown feats of raw strength, speed, agility and endurance, but his unique ability is his mastery of the smelting aura.
Endurance: As the strongest human, Zi Yu's endurance puts him on the level of the gods. After his first encounter with Shi Xing, he spent five years waiting in captivity to fight again  and was stronger than before after he broke out, even with minimal nourishment. He also fought Tian, immediately after fighting Zhen Chan and Er Chan, two powerful adversaries, without rest (he was healed by Zhen Chan after their fight). This occurred after he fought multiple great gods prior, in which he did not seem exhausted.
Enhanced Durability: In the beginning of the story, Zi Yu could be thrown into a wall by Shi Xing or receive a kick by the latter and come out the least bit affected. During the battle in the Gods' Domain, he was more durable than before as he was able to block a hit from an experienced great god with the Divine Power: The Indestructible, but only getting a light fracture. Plus, he received blows from Er Chan only to cough up blood.
Enhanced Speed: After improving his smelting aura, Zi Yu was so fast that even Shi Xing could not keep up before Zi Yu pierced him with his sword aura. He could also pick up a fallen body before it could hit the ground after coming from a considerable distance. After receiving Qiong Xiong Jie's soul power, his agility and speed increased so much so he was capable of dodging Tian's attack, while being fast enough to cut one of his dragons before he could be hit. His sword aura's speed increased later on in the story, after the fight with Tian, where he was capable of creating and recreating his swords before Wu Geng could react.
Enhanced Strength: Zi Yu is capable of lifting heavy individuals and objects; tossing Shi Xing, a large being, over his shoulders as well as lifting his Heavenly Punisher transformed into its defensive form, which weighs over a ton . He is also strong in parrying attacks from heavyweights like when he deflected Er Chan's physical attacks. After receiving a soul-power boost, he was capable of parrying Tian's attacks from his Blood Spear, even when it was surrounded by a lightning divine power.
Smelting Aura Edit
Sword Aura: Using smelting aura, Zi Yu can forge numerous airborn swords that be used for attacks. He also uses varius techniques with this.
- Meteor: Zi Yu summons a large amount of swords from the sky to rain down on his enemies.
- Piercing Heavens: An attack Zi Yu used on Shi Xing. Summoned a sword which shot upwards and had enough force to pierce Shi Xing's body. The attack was shown once and was remarked by Shi Xing to have been the expression of Zi Yu's anger towards what he did to him.
Heaven Punisher: Zi Yu's god slaying weapon forged from his smelting aura. A great sword wrapped in flames with the power to burn off the transcendent vigor and thus makes it a natural enemy to the gods. It's offensive power at it's peak was even able to injure Tian himself. Heaven Punisher also has a defensive form in which the flames are dispersed and the sword becomes extremely heavy and touch which not only allows it to be used as a means of protection from strong attacks but also it allows it to be used for very powerful swings (though they cannot be used multiple times due to the stress of the swing since it weights 1 ton).
- True Flame Heaven Piercer: A technique that Zi Yu uses with his Heaven Punisher. By increasing the
power of his flames, he is able to shoot out a burst of power from his sword which launches his flames outwards from the tip of his sword. The flames then fly around cutting the area around him causing damage to his enemies. This technique was even strong enough to escape Er Chan's Divine Skill: Wheel of Sin, which trapped Zi Yu in a world he created and not only did it destroy the world but also blasted and destroyed Er Chan completely. It's strength was also enough to injure Tian and spurred him to fight seriously. This has also shown to hurt half-gods as it was used effectively against Wu Geng, damaging him.
It is hinted in the manga that Zi Yu loved Wu Geng's mother, Da Ji. However, his little brother also loved her so he gave up pursuing her, though he never gave up his love towards her.
End of Shang Edit
Zi Yu returns to the city of Zhao Ge for the first time in 8 years in order to help Shou (Emperor Zhou) in his battle against the Gods after his declaration of rebellion. When he first arrives, he meets with Da Ji and the two share a brief reunion with each other. Zi Yu mentions that he can help her escape but she is resolved to stay and die with her husband. This leaves Zi Yu feeling envious of his brother as he leaves her to go to his side. He encounters Shou shortly and begins by lecturing him on how he is not a good father and how he has put the people of Shang at risk, which went against the promise he made with Shou to protect them as king. Shou disagrees and believes
that in order to protect his people, he must rise up against the Gods, for living as slaves and under their oppression is an even worse fate. Zi Yu simply remarks at how he hasn't changed but that he will die. Shou's courage is unhindered as they move out. Zi Yu enters the battle by attacking a few Zhao archers. Zi Yu is contemplative as Tian's dragon approaches the battle. The Gods arrive and Shi Xing blindsides him into a wall. Zi Yu unleashes his smelting aura upon the great god however, he manages to take each and attack and as both of them continue to clash, their battle is put to halt as Tian himself emerges from his Dragon and begins to battle against his brother. When Zi Yu notices his brothers danger, he attempts to rescue him by releasing a large smelting aura blade behind Tian, however, Tian's monochrome wall was far too strong for Zi Yu to get past and he was immediately defeated by Tian and left powerless to continue fighting and slipped into unconsciousness before his brothers death.
Ghost City Edit
After the battle at Zhao Ge ended, Shi Xing takes Zi Yu's unconscious body back to the Ghost City for the soul purpose of having another battle with the great swordsman. His life is saved thanks to Shi Xing's zombie's who were skilled in medical knowledge. Despite this though, Zi Yu suffered a lasting effect to his body that not even they were able to cure. The battle of Zhao Ge left Zi Yu unable to use his smelting aura due to Tian damaging his meridians and putting him in a state known as "shattered aura". A state where smelting aura users could not bring out their powers. Zi Yu fell into depression as he had lost everything from his freedom, powers and even his loved ones. During this period of time, Shi Xing would often talk to Zi Yu and mentioned how he kept Zi Yu alive because he knew that no matter how beaten down he was, Zi Yu would pick himself back up again and he would get an interesting surprise as a result. True enough, Zi Yu did not give up on life and slowly began to mend his meridians and retrain his smelting aura in order to create the ultimate sword. This would be his focus for the next 5 years inside the cell he was in. At some point, he was contacted by Da Ji's in his dream in which she told him of Wu Geng's arrival to meet Zi Yu one day and for him to protect her son. He is resolved to do so though once he awakens, he questions if the dream were true. Never the less, he focuses and almost completes his sword but his training is cut short when he meets Wu Geng at the peak of his imprisonment.
He immediately attacks him with a choke hold in his chains and smashes him into a wall knocking him out and then simply notes that the person he attacked was an ordinary person. Shi Xing amused remarks that the boy he attacked was another person apart of his game to which Zi Yu replies to him of it's stupidity. Shi Xing disagrees and notes that he's still waiting for Zi Yu to join it but he simply remarks that the day will come. When Wu Geng wakes up, he eventually realizes Zi Yu's identity but at best, he can only call out his name before he
is taken away to be apart of Shi Xing's game. This acts as a signal for him to come to realize that the person in front of him was his nephew that he was asked to protect. After some time, Zi Yu gets up and freezes himself from his prision cell and appears to save Wu Geng from Shi Xing. He explains that he is aware he is Wu Geng and he would like to hear what happened to him later. Quickly after, Shi Xing excited wonders if Zi Yu has regained his former strength to which Zi Yu remarks that he's gained just enough to defeat him. Excited, Shi Xing and his zombies make an attack on the two. During the course of his battle, Zi Yu destroys numerous Zombies and clashes head to head with Shi Xing himself. His anger at the humiliation he suffered over the years thanks to him made his attacks filled with a silent fury. However, despite Zi Yu's sword aura blades having such fury, they were still not enough to take down Shi Xing as his Desolate Wolves began to devour his sword aura which is continued to weaken him greatly.
Left with no choice, Zi Yu brings out his strongest weapon against the gods which he forged for the last 5 years. The sword known as Heaven Punisher which was imbued with flames that could burn away the gods transcendent vigor. Shi Xing intrigued by it's power clashes with Zi Yu once more however soon after a few moves, their battle is put on halt as Wu Geng unleashes his divine power monochrome for the first time. Leaving everybody shocked, Shi Xing makes his move to attack Wu Geng instead and he held off by him for a period of time. Confused at who Wu Geng truly was, Zi Yu remarks that he is the son of Emperor Zhou and what a great miracle it was for him to still be alive after they killed all of his family. Zi Yu then shortly attacks him from the back with Heaven Punisher. Shi Xing in his last moments before burning away notes that he isn't satisfied dying like this and wants to battle Zi Yu again but Zi Yu remarks that it's time for his "friend" to be put to rest and that they will meet once again in another world as he says farewell and leaves nothing but the bones of his body behind. Shortly after Shi Xing's death, the Ghost City begins to sink into the sand and enter a portal into the world of death due to Shi Xing's Mark of Death not being active anymore. Zi Yu in a last ditch effort manages to knock Wu Geng with a punch out of the sinking city and is shortly presumed to be dead as his nephew grieves his death. Zi Yu then immediately shows up remarking he's fine and he escaped shortly after he saved Wu Geng. After that, he walks along with Wu Geng and Yun Zhong Zi as they brief each other on what happened.
Season 2 Edit
Phantom Island Edit
During this period of time, Zi Yu separates from Wu Geng and tells him to meet him once he finishes handling his business with Bai Cai in order to begin his training with smelting aura. He once again appears on a small boat to pick up Wu Geng and take him to Phantom Island. He mentions how he is unsure of how much progress Wu Geng will make training there while they set off together. He also notes that even his own training is incomplete and that he hopes that this will allow them both to develop faster through the experience. Having lived for one year there in the past, Zi Yu's expertise would also be key for training Wu Geng and he noted to him that he would be a strict teacher and that he will have to obtain great power if he is to reach the End of the Earth in the Gods' Domain. Wu Geng remarks how at a time like this, Zi Yu should at least try to say something encouraging at times like this as they begin to enter the island.
Season 3 Edit
Zi Yu returns from his training to face off against Chi Long.