"King of Killers" Cesar is a 6000 years old assassin and head of "Sabre" assassin organization.
Cesar appears to be thirty or forty years old. He wears a loose-fitting long robe, and his arms were hidden by the sleeves of the robes and crossed over his chest.
Cesar is a generally lazy man who loves to spend most of his time chasing after women or immersing himself in his hobbies like admiring sculptures. However, even then he likes to call himself a man of principle, like when he didn't reveal the content of Delia's note to Linley.
Born in the Yulan continent, he is more than 6000 years old. He was at the peak of the Saint level for five thousand years, before breaking through to the Deity level and becoming a Demigod on his own.
When the Debs clan decided to task his "Sabre" organization with destroying the sculture, "Awakening From the Dream ," as well as killing Linley Baruch the representative, Mr. Bayonet, refused, and quickly informed the Old Master, or Cesar. Thus, Cesar decided to personally visit the Proulx Gallery, to protect it himself, resulting in him splitting four members of the "Bloodrose" Organization in twaine. This all was due to his love of art and sculpture.
During the auction of the sculpture "Awakening Drom the Dream," Cesar gave a stunning bid, after a short halt when Kalan Debs bid 8 million gold coins, of 10 million gold coins. After that sudden increase in value, Delia Leon started a bidding fight with him, with the eventual victory of Delia's, due to a certain letter she gave him, causing Cesar to laugh, and give her the win.
Later, Cesar decided to pay Linley a visit at his home. This is the first time he meets Linley in person, and also when we first learn his name, Cesar. It is also revealed that he was already a saint level combatant back when Doehring Cowart was alive, meaning he is about six thousand years old. In the end of the chapter, he asks Linley when he and Delia are getting married, even though they aren't in a romantic relationship, hinting at the contents of the previous note he was given by the latter.
When Linley asks him the matter of why he thinks Delia is his fiancée, Cesar is amused, but still doesn't reveal why he thought so, thinking himself as a principled man. It is also revealed that Cesar had killed a Cardinal of the Radiant Church in the past, and had stolen his medalion, thus revealing why he had it in the first place. Finally, he reveals the reason of his visit. He wanted Linley to scuplt a sculpture of himself, capturing the aura of when he's at his manliest, being when he kills someone. To show Linley his aura when he kills someone, he demonstrated it on a vase. As he kills, he becomes cold, void of any emotion, and his target seems to become the only thing in the universe to him. Only after the vase is disintegrated does he return to his normal, playful self.
After Linley accepts the sculpure request, it is in turn time for him to name the prise. At first, he requests that Cesar capure King Clayde, so that he can interrogate him, and most likely kill him, but Cesar refuses due to the impact killing a king would cause. Klling a king, compared to a cardinal, would cause much more chaos in a kingdom, since a Cardinal is much more easily replaced. Killing a king would cause fighting and conflict, so Cesar refuses so that he doesn't cause unnecesarry hostility between the Radiant Church and his own "Sabre" organization. Instead, he agrees to give Linley the recipe to a poison that would seal 90% of a warriors power, making it much easier to kill them.
Several years later, Linley finally meets Cesar again, after he attemts to save the Barker brothers. However, unluckily for Linley, Stehle, a Saint, was there to guard. As Linley and Stehle fought, he came a hairs breath away from killing Linley. However, just as the sword was about to pierce Linley's head, everything suddenly freezes. As it turns out, Cesar had arrives just in time, and he had even entered the realm of Deities, two years prior.
As Cesar has arrived, Stehle has no choice, but to let Linley go. However, he asks to at least get the Barker brothers with him, and initially, Cesar agrees. However, as Cesar gets a closer at the brothers, he suddenly tells Stehle to leave, not allowing him to take the broters, without even giving him a reason as to why.
As it turns out, the Barker brothers were the descendants of Cesar's closest friend, Armand, the Undying Warrior of the Supreme Warrior Clans. Thus, Cesar gives them the Secret Undying Warrior Manual.
He relies on a Divine Spark to become a God.
When Linley had freed both Dylin and Tarosse form their Soulseed, he left Miluo Island and headed towards the Indigo Prefecture accompanied by all his relatives, including Cesar.
He never learns of the death of his beloved Cecily in the story since Linley decides it's best to let the matter rest.