————The name "God of Sin" was never unfamiliar to Rozen.
During the Blazing Banquet, when dealing with the Original, Rozen had performed the Taizan Fukun Ritual using Kinu and Gyokuto as mediums to summon a god capable of opposing the Original. At that time, the Original had addressed this deity as:
"God of Sin!"
////Back then I couldn't find the translation so I translated as Tomagmi/God of Fault.////
This was the divine name that echoed throughout history.
"As you likely know, the Fourth Primogenitor was created by the Devas and the Three Primogenitors as a god-slaying weapon," Kuraki Shirona had explained while they were still in Kamioda Shrine's main hall, discussing The Cleansers.
"Then which god was this weapon created to slay?"
This was a question most overlooked. When speaking of the Fourth Primogenitor as a god-slaying weapon, no one questioned which god it was meant to kill.
The Devas were ancient superhumans, descendants of demigods who had built a prehistoric civilization far surpassing modern technology. For such beings to create an ultimate weapon capable of god-slaying wasn't surprising.
In other words, "god-slaying" could have been just an expression.
But what if it was literal?
If the Devas and Three Primogenitors truly created a weapon to kill a god?
Then the Fourth Primogenitor's existence took on entirely new meaning.
Kuraki Shirona knew these secrets. Few realized she possessed dual consciousness - her clan passed down spiritual power and memories through generations by inheriting an ancient ancestral personality.
Thus, two personalities coexisted within her: the ancient "Dark Consciousness" passed down through generations, and the consciousness of her physical body serving as its vessel. Her old-fashioned speech patterns came from this ancient consciousness inhabiting a young body chosen by her family.
As this ancient consciousness, Kuraki Shirona knew many forgotten secrets, including one of the world's greatest:
"Legends say in ancient times, gods ruled from the heavens before humans existed."
"Among them emerged an outlier who fought other deities, was exiled to another world, yet returned through sheer power to wage war against the gods, slaughtering many."
"This deity became the progenitor of Demons, the original sinner."
"His name was Cain."
"Also known as... the 'God of Sin.'"
At this, Kuraki Shirona looked meaningfully at Rozen, who fell silent. He had met this god - even knew his current whereabouts.
"The God of Sin Cain's power was overwhelming," Kuraki Shirona continued. "As gods fell before him, the Devas and Three Primogenitors created their god-slaying weapon."
This weapon became the Fourth Primogenitor.
"Holy Annihilation originated from the God of Sin and the Fourth Primogenitor's massacre - beginning, revolving around, and ending with these two."
Ultimately, the Fourth Primogenitor succeeded in killing Cain, then turned against the Devas and was sealed, divided into twelve Matrices hidden worldwide.
Yet nearly a year ago, both had revived - the Fourth Primogenitor during the Blazing Banquet, and Cain's spirit through Rozen's Taizan Fukun Ritual, which had possessed Kojou before falling dormant.
The two arch-enemies at Holy Annihilation's center had both returned, only to be sealed again.
The Fourth Primogenitor was sealed by the Witch's brother, hailed as The Divine Child of Origin for arriving with divine aura and protection.
Cain was sealed within an ordinary boy, now called The Divine Child of Cain.
Thus Rozen and Kojou became globally famous.
"The Cleansers are Cain's worshippers - terrorists seeking to recreate Holy Annihilation," Kuraki Shirona explained. "They aim to eradicate all Demons, restore humanity's original form, and return the world to an era without Demons or magic."
Rozen initially thought he'd misheard.
"If Cain is the progenitor of Demons, why would his followers want to eliminate Demons and magic?"
Yet neither Kuraki Shirona, Vatler nor Iblisveil found this strange - the contradiction notwithstanding, The Cleansers' goals were genuine.
"Cleansers call themselves Knights of the Sinful God, wielding artifacts Cain brought from another world," Kuraki Shirona revealed the key point.
"That world had no supernatural powers. As the god who created Demons, Cain's artifacts can nullify all magic and supernatural abilities, even granting life to objects to fight for him."
This explained the wyverns and the foreign mana erosion. Recognizing these, Kuraki Shirona confirmed Knights of the Sinful God had sent the wyverns to delay Rozen.
"They undoubtedly seek Holy Annihilation's legacy in Shinjin Lake - to reclaim Cain's relics or power for their goals."
She warned Rozen: "After the dragon, they'll target Itogami Island - both Kojou who seals Cain, and you who seal the Fourth Primogenitor. Be cautious, Divine Child."
This conversation had prompted Vatler and Iblisveil to act - as Cain was whom the Three Primogenitors had sought to eliminate by helping create the Fourth Primogenitor.
Rozen couldn't remain passive either - The Cleansers threatened everyone he cared about.
Now, he finally faced them.
The three attacking the dragon from Shinjin Lake were the Knights of the Sinful God themselves.