Throughout vol 6 (or 7?) through to 10, Kanone took over the entire school, threatening to kill everyone. And he was successfully subdued in vol 10. I dunno how they did it because in my stupidity I skipped 10 and bought 11 and 12.
Anyway, this brings us back to the question. Why did Kanon betray the Blade Children? In his conversation with Eyes, he mentioned that he was with the Blade Children all along, until he met the enigmatic character only known as "Hizumi." This Hizumi character made him realize what evil existence the Blade Children are, and he’s determined to put an end to them himself.
There's this other group called the "Watchers" who watched this whole event unfold, and only broke silence to Ayumu after Kanone was apprehended. The Watchers' representative Tsuchiya Kirie, along with Eyes Rutherford, revealed the truth to Narumi Ayumu...
Eyes began with this, "Narumi Ayumu, do you believe in a 'creator'?"
An all-powerful creator who created the all life and everything in the universe. One day, that creator, out of his whim, decided he’ll try to destroy mankind. Now the creator understand that great natural disasters won't work, because humans are great at surviving and adapting...so the creator decides to destroy mankind from within. He sent to the world all-powerful demon: "Mizushiro Yaiba:” born to Japanese parents For some reason he was born with a rib missing. He’s the father of all the Blade Children.
Mizushiro Yaiba was a child prodigy, and excelled at everything. He grew up to be an adult with a certain kind of charisma. When Yaiba was 23, he formed a group called "Knights," with him as leader. No one really knows what the Knights does, but Yaiba, with his talent, took control of the financial and political scene, and his group grew bigger and bigger. By the age of 26, Yaiba had become the undisputed ruler of the world in shadows. But as powerful as he is, it's still impossible for one man to defeat several billions of people in the entire world. In order to destroy the world, he started the "Blade Children" project at age 29. It's a project to "mass-produce Yaiba's children": Yaiba means "Blade" in Japanese. The Blade Children are Yaiba's children
Many people wanted to inherit Yaiba's lineage. Through artificial fertilization and test tube babies, they willingly carried out Yaiba's seed. About 80 Blade Children were born through this. Those who willingly carried out the project had no idea of Yaiba's true intentions. They thought that with Yaiba's talent multiplied, they could change the world for better...
Yaiba's children, The Blade Children, for identification purposes. had one rib removed surgically as soon as they were born…
The project was a great success. As the children born of this project all inherited the Yaiba's great talents. However, some members of the project sensed that something was going on. Of all the children that were born, all of them inherited the talent: genetically speaking this is rather abnormal. In the evolution of mankind, the Homo Sapiens won over Neanderthals because they were better and fiercer. Could this be that Yaiba's trying to create a superior race and using them to wipe out the inferior?
It also turned out that Yaiba's talents is inherited through every generation. The number of Blade Children continued to increase after the second and third Blade Children project....
The doubters confronted Yaiba, and asked what he’s plotting. Yaiba told them each and every detail with a smile, along with the lines: "My will is to wipe out mankind, and my blood carries that will. Adult Blade Children will act to destroy mankind. There's no running away."
All of Yaiba's Blade Children are born to have a certain distaste for common people. But they are not always like that. It is said that even Yaiba himself was not like that before the age of 20. But when the Blade Children reach a certain age, all those who have inherited Yaiba's lineage would awaken and proceed to act as Yaiba wills: to facilitate the destruction of mankind.
People who remained with Yaiba asked him why would he reveal his plan to those who oppose him, and he replied, "This is just to make sure that the game is a little more difficult to clear, otherwise it'd be boring."
The group soon broke into three parts.
Those who fear the project and Yaiba's existence and want them quickly eliminated, became the "Hunters."
Those who thinks that the project is still in its middle stage, so they should continue monitoring the children and see what happens, the "Watchers."
And finally, those who support Yaiba's plan no matter what, the "Saber."
This breakup of the group is all just entertainment to Yaiba. The Hunters tried to purge the Blade Children, some as young as 5. During this initial purge, about 20 were killed. Of course the Hunters tried to target the source of all problems: Yaiba himself, but they were at a disadvantage in the beginning - No man can kill Yaiba. Yaiba would have a hunter point a gun at his head, but for some reason the hunter can just never pull the trigger to kill him. No bomb or blade can hurt Yaiba, it's just his innate immunity to harm.
The Hunters factions were cornered, and all seemed lost as Yaiba continued with his Blade Children. At that moment, one unexpected 20year old Japanese man appeared. He easily killed Yaiba, who died with an unbelieving look on his face. That man is Narumi Kiyotaka
Yaiba could not be killed by mankind. In the Bible, a rib was taken from Adam to create Eve, so that he could reproduce. Yaiba reproduced without Eve, then why is a rib missing?
Just as there is god and devil, good and evil, there are two creators on the opposing end of the spectrum . One created Yaiba to destroy mankind, the other took a rib from Yaiba to create Narumi Kiyotaka. It's like a chess game.
At the moment of Yaiba's death. This whole matter should've been easily solved by killing all the Blade Children, which the Hunters wanted to do. However, the Watchers and Sabers would not have them kill the remaining 50 Blade Children, who were all no more than 6 year old. They wanted to find a way to save the Blade Children without killing them and asked Kiyotaka for help. But Kiyotaka was powerless in such a problem: he’s a "destroyer," born to destroy Yaiba and has no power to release his heir. But he showed the watchers and sabers a glimpse of hope: one who is Narumi Kiyotaka, but is not Narumi Kiyotana - one who is not like god, but not god, and has powers like god: Narumi Ayumu. Ayumu was created to save the Blade Children.
Of course not everyone believed that, so some continued to hunt down the Blade Children, but some hunters switched and joined the Sabers or Watchers....
Tsukiomi Academy was a school run by the Knights before the rift, therefore a large number of the Blade Children were assembled there. Kiyotaka sent Ayumu into this school in order to slow down the Hunters' progress, and also give him problems so that he would mature and grow from them. He has developed a personality that would cause him to fight the Hunters whenever someone gets murdered with no reason.
But there something in Kiyotaka's plan that he didn't tell anyone, and that's the reason why Kanon went berserk. It turns out that Kiyotaka never really planned to save anyone, he’s just wasting time so that Ayumu can mature to his true purpose: like Yaiba and Kiyotana, Ayumu has his opposite: Mizushiro Hizumi, Yaiba's brother. This is just a recurring game between the two opposing creators. But some like Eyes still continue to believe in Ayumu even though he’s just a false hope, for those who have no hope, it is better to believe in a false hope than nothing at all.