Back when Rozen was still training in the Akabane household, Tenzen had already been deliberately cultivated by the family. For that purpose, they did not hesitate to send him into the military to build strong ties with them.
Tenzen, with such a background, knew very well just how powerful and influential Izanagi was in Japan. For the Akabane clan to oppose them would be nothing short of seeking their own destruction.
Just as Tenzen said, once the Akabane clan decided to go down that path, their annihilation that night was inevitable—without any suspense.
Therefore, Tenzen resolutely chose to throw his lot in with Izanagi and take advantage of the chaos to fish in troubled waters.
"I also thought about having the clan members fake their deaths or pretend to be dead, but Izanagi's people are onmyoji to begin with. They manipulate miasma, the energy of death, and control shikigami, which are akin to corpse-spirits. How could they possibly be fooled into not telling real death from a fake one?"
Because of that, faking or disguising death simply wouldn't work.
Besides, even if they managed to fake it successfully, where could they hide all the members of the Akabane family?
The enemy was a clan that stood as the cornerstone of the nation—noble blood symbolizing Japan itself. The entire country was essentially their territory. How could the Akabane clan hide that many people and expect not to be discovered?
It was an utterly impossible task.
So, Tenzen had long come to terms with the fact that saving everyone was out of the question. He could only try to save as many individuals as he could.
Rozen was one of them.
If Tenzen hadn't defeated him and made him fall into the sea of fire, the person who would have appeared in front of Rozen at that time would have been someone from Izanagi. They would definitely have killed him.
Raishin was another.
Just like Rozen, Raishin had sensed something was wrong at home and rushed into the inferno. If Tenzen hadn't intervened and made him believe it was Tenzen who had slaughtered the clan, Izanagi would never have let a single Akabane clan member who knew the truth survive.
It was precisely due to Tenzen's maneuvering that Rozen and Raishin survived, each under the justification of either "lacking the Akabane bloodline" or "having no talent for magic."
Had they learned the truth, both of them would surely have been silenced. With that in mind, Tenzen stepped forward and willingly took the blame as the one who destroyed the clan.
And then...
"Besides you and Raishin, I could only think of a way to save one more person."
Tenzen shifted his gaze toward the girls in the combat unit.
Seeing this, Rozen, who had already suspected as much, remained silent.
The reason was simple.
"Since you said it's impossible to fake death in front of Izanagi," Rozen said quietly, "then the person had to actually die. But once someone's truly dead, there's no bringing them back."
In this world, the definition of the soul is still ambiguous and remains unconfirmed.
Whether souls truly exist is something no one can say with certainty.
Given that, resurrection is considered an impossible miracle in this world.
Thus, Tenzen couldn't truly kill the person he wanted to save, yet he had to make them "die" in order to deceive Izanagi.
Such contradictory goals—how could one achieve them?
Tenzen came up with a way.
That was—
"To split 'this person' into several parts and 'raise' them inside automatons, turning them into living material components of the dolls. This created the fact of her death while also allowing her to continue existing in another form—maintaining the freshness and vitality of the body through puppet activity and the circulation of mana until she could be reassembled and revived."
Rozen's words were shocking to the extreme.
But that was the truth.
"The brain is inside Hotaru, the heart inside Mitsubachi, the sensory organs in Kamakiri, the muscle fibers in Kagerou, the digestive organs in Tamamushi, and the nervous system in Himegumo."
Tenzen calmly listed facts that made the girls in the combat unit tremble.
He had indeed affirmed Rozen's claim.
In other words, Tenzen had housed the person he wanted to save inside the bodies of automatons in a distorted form of survival—neither fully alive nor completely dead, blurring the boundary between the two in order to fool Izanagi's people.
However...
"The body can be preserved, but the soul cannot." Tenzen said with a bitter smile. "It's a concept that hasn't been confirmed by anyone, but it definitely exists. Otherwise, if simply reconstructing the still-active body could bring a person back to life, automatons wouldn't need Eve's Heart to be granted will and life."
Once someone is dismembered into that many pieces, how could they possibly continue living?
Even if the body could keep moving, the soul, without a vessel to cling to, would be lost and complete resurrection would be impossible.
Perhaps others couldn't confirm the soul's existence, but Rozen could tell everyone with certainty—the soul exists.
Therefore, from the moment "that person" was disassembled, she had become both alive and dead—both were facts.
Tenzen could preserve the body and piece it back together, but to fully bring her back, the soul must be recovered.
This was the reason Tenzen betrayed his country, came to this land, enrolled in the Academy of Machinart, and participated in the research of the "Sanctuary of Fools."
"Androgyne—the essence of that research is the creation of artificial souls."
Rozen revealed the secret.
"Through this research, you could gain technology related to the soul and attempt to retrieve Nadeshiko's soul."
Yes.
Tenzen wanted to bring Nadeshiko back to life—his own sister.
Raishin had said he saw Tenzen dissect Nadeshiko with his own eyes and turn her into a banned doll. That was the truth of the matter.
The real reason Tenzen gave the Keystone to Rozen was because he hoped Rozen might be able to analyze it and help achieve his goal of retrieving Nadeshiko's soul.
"Even now, despite all our research, we haven't been able to fully analyze what a soul really is, what it's made of, or how it works," Tenzen said.
"But if we use the principle of 'transposition' magic, even without fully understanding the soul's composition, we can still pull it back into the world of the living. That's a type of transmutation magic."
This kind of magic involves transforming one substance into another.
For example, turning stone into bread, swords into guns, minerals into gold, or air into poison gas—this is an application of Alchemy.
What Tenzen wanted to do was very simple.
"It's hard to turn stone into bread, but turning bread into bread is much easier—even if they're different types of bread."
In other words, Tenzen intended to use his own soul as a sacrifice to swap and bring back Nadeshiko's soul from the underworld.
This method bore a striking resemblance to the life-for-a-life principle in the Taizen Fukun Ritual.
"The problem is, ordinary matter can't hold a recalled soul. To capture Nadeshiko's soul, we need a means to grasp something that has no physical form."
And as it happened, the Akabane clan had just such a method.
In the past, hadn't Rozen used it to capture the summoned Kinu and Gyokuto from a divine descent ritual and seal them into jujutsu tools, giving them physical form?
That method was—
"The Crimson Wing Formation — our only remaining hope."