Having formed a contract with demons, witches are able to wield power equivalent to that of demons through their guardians, who are their demon vassals.
They can harness magical abilities surpassing even the highest-ranked mages, reaching a level comparable to high-ranking demons, and even rivaling the most powerful vampires, earning them the title of "witch."
As a price for obtaining this power, they must all fulfill the terms set forth in the contract when it was formed.
For example, Tokoyogi Yuuma's price was to release the prison barrier and internalize the absolute command, dedicating her life to fulfilling this command, which enabled her to gain the power to manipulate space.
So, what price did Minamiya Natsuki, whose abilities surpassed even Tokoyogi Yuuma's and who was feared by European demons as a demon slayer, pay to obtain such power?
It's important to note that the power of witches and their guardians depends on the magnitude of the price paid. The greater the price, the greater the power, both for the witch and the manifested guardian.
Natsuki's Rain Gold has the power to destroy Itogami Island with a single strike, almost comparable to a primogenitor-level beast vassal, which even Dimitrie Vatler, regarded as the closest to a primogenitor, takes seriously. Considering this immense power, what could Natsuki's price have been?
Rozen had once speculated about the price Natsuki paid to gain her current power.
This mystery has finally been revealed.
The price Natsuki paid was to become the guardian of the prison barrier and spend her entire life in slumber here.
She enjoys such great privileges within Itogami Island, able to squander such wealth, because the Artificial Island Management Cooperative relies on her power to imprison heinous magical criminals. Thus, they are obliged to grant her requests.
Her powerful space manipulation magic is also intended to bring criminals here for imprisonment.
No one knows where the prison barrier is located, not only because it exists in a different dimension, but also because it is Natsuki's dream world. Besides her, no one can find it, let alone touch it.
As Tokoyogi Yuuma said, in order to build an absolutely secure prison, the Artificial Island Management Cooperative prepared a witch and had her pay the price of sleeping here for life to manage and guard this place, while granting her as many privileges and status as possible outside, which created everything we see now.
The anomaly Rozen noticed about Natsuki when he was young was because she had just arrived here to fulfill the contract, and she had created a puppet through magic to return to Rozen's side, and even honed it to be almost indistinguishable from a real person, living with Rozen through dreams.
This is the truth behind everything.
Natsuki's disappearance was probably also due to the abnormality in the space on Itogami Island, as the prison barrier began to manifest externally. To maintain the existence of the prison barrier, she had to focus all her attention here and could not manipulate her doppelganger anymore, diverting all her energy to this side.
Unfortunately, in the end, the prison barrier was still found.
"As a pure-blooded witch, Minamiya Natsuki's fate is similar to mine, predetermined even before birth."
Tokoyogi Yuuma bowed to Natsuki while speaking and gazed at her.
"Perhaps she once lamented her fate and felt that life had no meaning because she was destined to sleep here and could never leave. In addition, since this is a different dimension, time flows differently here than outside, allowing her to maintain this appearance forever while asleep."
This is also the reason why Natsuki's appearance has remained unchanged from the past to the present.
As long as she continues to sleep here, Natsuki can have eternal youth.
But that is definitely not a good thing.
"Eternal youth means eternal slumber. Her dream will continue for eternity, never waking up, never ending."
The price paid by Natsuki's contract is so great that she can exchange it for such powerful abilities.
Naturally, Natsuki's status and power on Itogami Island also come from this.
Otherwise...
"How can a mere witch protect her brother from the malice of numerous forces worldwide?"
Tokoyogi Yuuma's words cut deep into Rozen's heart.
"Her life has no meaning, and even if it does, it's not the meaning she should have. Besides this dream world, she has nothing."
Tokoyogi Yuuma turned his head and looked at Rozen.
"But your appearance has given 'Witch of the Void' the only meaning in her life."
Perhaps this is the only meaning that Natsuki can find from becoming the key to the prison barrier.
By using her identity and the price paid, Natsuki can protect Rozen, ensure his safety, and even provide him with a place to stay on this island.
This is a meaning that Natsuki did not have before meeting Rozen, an existence.
Therefore, for Natsuki, Rozen is everything.
If Rozen were to encounter trouble, whether from the Lion King Agency or the Artificial Island Management Cooperative, Natsuki would dare to warn and challenge them. Even if there are many colleagues, students, and acquaintances she values on this island, if it involves Rozen, Natsuki will spare no effort, even if it means abandoning everything.
In the beginning, Natsuki warned Shizuka Koyomi of this resolution before the "Blazing Banquet" began.
It's not that Natsuki didn't invest emotions in people other than Rozen, but Rozen's importance has reached the point where Natsuki would do anything, even abandon those emotions.
Everything is because of Rozen's appearance, injecting Natsuki's cruel fate and life with the only meaning.
For this reason, Natsuki did not hesitate to step into this place after graduation, and has been sleeping here for the past ten years, continuing to protect Rozen and helping him grow up in her dreams.
If it weren't for her identity as the guardian of the prison barrier, Natsuki would really not be able to protect Rozen from so much malice.
In view of this, Natsuki does not regret becoming the key to the prison barrier, but rather feels fortunate.
This is also the reason why Natsuki does not want Rozen to know about her situation.
This is the path that Natsuki has chosen.
But...
"Do you want to watch her keep sleeping here forever?"
Tokoyogi Yuuma looked at Rozen and spoke sincerely.
"If it's now, with the beast vassal of No. 6, we can completely cut open Minamiya Natsuki's dream and wake her up."
At that time, Natsuki would no longer need to sleep here forever.
And the prisoners imprisoned in her dream would be liberated.
This is mutually beneficial.
Tokoyogi Yuuma then made such a request to Rozen.
"So, don't interfere with me. This is also for your own good, Minamiya Nichiyo."
After speaking, the vassal of No. 6 by Tokoyogi Yuuma's side erupted with magic, summoning the rainbow-colored Valkyrie.
The Valkyrie raised her sword high and struck down towards Natsuki, who was sitting in the chair, sleeping.
"Stop!"
"Don't!"
Both Kojou and Avrora called out.
But Rozen did not make any move.
Just because...
"Clang!"
A tri-colored light sword met the falling rainbow-colored light sword, creating a crisp clash of swords.