At that time, Rozen had just returned from the Izanagi clan. In preparation for his meeting with Tenzen where he would reveal the full truth to Raishin, he sought out Shouko. He first asked Raishin—who was serving as Shouko's guard—to wait outside, as he had matters to discuss privately with her.
Shouko showed no surprise. Instead, she seemed to have already steeled herself for this moment, quietly waiting for Raishin to depart before meeting Rozen's gaze.
"So, what did you wish to discuss?"
Shouko cut straight to the point.
Notably, she no longer addressed Rozen with her usual playful "little boy" epithets. She had realized Rozen had come to demand answers.
After all...
"I must choose my words carefully when speaking to one of the Order of the Rose's witches—the esteemed Karyuusai Shouko, known as the Red Rose. Wouldn't want to cause offense."
Rozen's calm declaration instantly shifted the atmosphere, weighing it down with palpable tension. Yet every word was undeniable truth.
"...So you've uncovered everything."
After a moment's silence, Shouko smiled enchantingly and admitted it.
The foremost automaton craftsman in the world, the legendary Karyuusai, was indeed one of the Order's leaders—the Red Rose.
"Though 'leader' overstates my involvement. I've little interest in the Order's political machinations. Were it not for their status as the oldest magical organization—and the forbidden techniques I could acquire through them—I'd never have joined."
Shouko spoke with effortless grace.
In other words, while she bore the title of Rose Witch, her relationship with the Order was purely transactional.
Unlike her fellow Roses who sought political dominion, unlike Astrid who spread terror, or even unlike Domon Kira who sought to preserve her clan, Shouko had only one objective:
"The Machine Doll."
The words rolled slowly off Shouko's tongue.
"That alone holds my interest."
Naturally. As an automaton craftsman, how could she remain indifferent to the Machine Doll?
However...
"I seek to create a Machine Doll through my own power, not steal another's achievement. That's why I joined the Order—to acquire the necessary knowledge and techniques."
As she spoke, Shouko studied Rozen's reaction.
"You've already deduced this much, haven't you?"
Rozen nodded silently.
He had indeed discerned Shouko's motives.
The proof lay in...
"Your Setsugetsuka series have been siphoning my life force all this time."
Rozen revealed this shocking truth—something he'd noticed long ago.
"When I first began using Yaya properly, I kept sensing something..."
What exactly?
"The sensation of my vitality being drained."
Whether using Yaya, Irori, or Komurasaki, Rozen had consistently felt something within him being absorbed. That "something" was his life force, being drawn by Shouko's masterwork automata—the Setsugetsuka series.
"Initially, I assumed this was the price of using banned dolls."
As previously explained, banned dolls were forbidden not just because they required living human components, but also because their creators often incorporated dangerous elements or sacrificed crucial aspects in pursuit of power.
Some were designed for energy efficiency at the cost of mobility. Others had their emotions suppressed for easier control. Certain models required blood to maintain biological activity. The most extreme even demanded human sacrifices to power their magic.
Rozen had assumed this life-draining effect was simply the Setsugetsuka's unique cost for unleashing their full power.
However...
"Had this been an intended feature, I would have found records of it when studying the secret texts in your manor. Yet the manuals mention nothing of such a requirement, nor does it align with the Setsugetsuka's design philosophy."
Having fought alongside the three sisters countless times, Rozen understood their construction better than they did themselves. Combined with his study of the secret texts, he could confirm this life-drain was no intended function.
Unless...
"It's not an operational cost, but payment for something else."
Rozen enunciated each word carefully.
"Such as... evolution."
Precisely.
Evolution.
Rozen had discovered that Shouko's creations possessed this capability.
"This must be the portion of the secrets not recorded in the texts, correct?"
While Rozen had mastered over ninety percent of Karyuusai's knowledge, certain crucial details about the Setsugetsuka series remained undocumented.
Now, Shouko herself would unveil these secrets.
"You've surely noticed—the three sisters' magic circuits are extraordinarily powerful. To fully utilize them requires mastering the final stage of Mind's Eye."
Shouko spoke without further concealment.
"These circuits were all created based on the principle of Phase Transition."
—Phase Transition.
The ultimate technique of Karyuusai, the pinnacle achievement of the world's greatest automaton craftsman.
"Automata equipped with Phase Transition can absorb their user's life force. By assimilating living spiritual energy, they shift their phase—becoming more human-like, transcending Euclidean space and physical laws until they become indestructible, evolving into higher lifeforms."
Meeting Rozen's gaze with a radiant smile, Shouko declared:
"In other words, given sufficient life force, all three sisters could eventually become Machine Dolls."
Rozen had once speculated Yaya might be the prime candidate to become a Machine Doll.
He was wrong.
All three Setsugetsuka sisters were primary candidates.
"Father Time's prophecy stated the Machine Doll would emerge during this Night Party, and that the Wiseman would obtain it." Shouko's voice brimmed with yearning. "I've always believed the prophecy referred to one of the sisters—especially Yaya, as she best fits the criteria of 'Flawless Jewel.'"
That's why Shouko had entrusted Yaya to Rozen.
Her plan was for Rozen to compete in the Night Party with Yaya, become the Wiseman, and ultimately guide Yaya's evolution into a Machine Doll—along with Irori and Komurasaki.
This was Shouko's true purpose in gifting Rozen the Setsugetsuka series.