Akatsuki Residence, Nagisa Akatsuki's room.
At this hour, Nagisa had only just drifted into deep sleep.
Her childhood friend had come to Itogami Island after so long, and they were even sharing the same room. Since both girls were natural chatterboxes who loved to gossip, there was little chance they'd simply turn in early.
Nagisa had made a show of telling everyone that they needed to sleep early tonight so they could get up early tomorrow—but in truth, she was still a fourteen-year-old girl. In a moment like this, how much self-control could she really muster?
Couple that with her being a motor-mouth by nature, and it was no surprise that she and Yuuma Tokoyogi had talked late into the night. Only just now had Nagisa finally started to feel drowsy, lying down and slipping into dreams.
She didn't notice that her childhood friend hadn't fallen asleep at all. Instead, Yuuma stood by the bed, quietly watching her.
"Honestly… Nagisa hasn't changed a bit—once she starts talking, she can't stop."
Yuuma gave a wry smile. Her gaze held nostalgia, fondness, and more than a touch of helplessness.
Reaching out, she brushed a stray lock of hair from the peacefully sleeping girl's face, murmuring to herself with a complicated expression.
"Why did it have to be you, Nagisa…? Why did you have to become the Fourth Primogenitor?"
When she'd first heard the news, Yuuma could hardly believe it.
Her childhood friend—a girl she'd laughed and played with—had become the vessel for the strongest vampire in the world, a being of legend, sharing her body with that existence. The thought felt more absurd than any fairy tale.
"Not that I'm any better…"
The moment she thought of her own origins, Yuuma's face grew even more complicated.
Nagisa and Kojou probably wouldn't believe it either—
That their childhood friend had never been an ordinary girl.
And now, she, an outsider who'd never been "normal" from the start, was about to make a move against her friend, who'd stopped being "normal" along the way.
"Don't hate me for this, Nagisa."
As she whispered, the space behind her began to shimmer faintly, rippling like the surface of a pond.
From the far side of that ripple, something slowly emerged, as though rising from the depths of a dark lake.
A massive knight, its entire form a cold, azure blue, radiating a fierce, malevolent aura.
Clad head to toe in armor, it wore an ominous, skull-like helmet devoid of a face—only an unfathomable darkness within.
Anyone who had seen Natsuki Minamiya's guardian would be shocked by the sight, for this towering Blue Knight's presence and appearance were eerily similar.
Clearly, this too was a Guardian.
And there was only one kind of being who could possess such a thing—
A witch.
"Do it, Le Bleu."
Yuuma pointed toward the sleeping Nagisa and issued her command to the Guardian.
Unfortunately for her—
"I'd stop right there, if I were you."
Just as the azure Guardian reached out toward the bed, a voice spoke from behind her.
"…!"
Yuuma's expression sharpened as she spun around.
The window was somehow open, curtains fluttering in the night breeze, and a figure had arrived as silently as moonlight on water.
"It's you?" Yuuma's face tightened, her body going on alert—then she smiled faintly. "I knew you'd show up."
"Oh?" Kaiser arched a brow. "So you know who I am."
"Yeah. Someone told me." Yuuma's smile turned casual, almost teasing. "Never thought a government agent from the Lion King Agency would come to spy on my childhood friend. If my identity could be made public, I'd file a formal protest."
"Too bad your identity can't be made public." Kaiser's tone was flat. "I bet even the Akatsuki siblings don't know their childhood friend is a senior officer of the Library—LCO."
"The 'Azure Witch,' Yuuma Tokoyogi."
"If they found out you were part of a criminal organization, both Nagisa and Kojou would be stunned."
Yuuma fell silent.
Behind her, the Guardian radiated menace, itching to strike—either at Kaiser or at Nagisa.
But Yuuma didn't move. She only sighed.
"If I told you I didn't become friends with Kojou and Nagisa because of some ulterior motive… would you believe me?"
"I would," Kaiser replied without a trace of surprise.
He knew her backstory all too well.
"Ten years ago, the Grand Librarian of LCO, Aya Tokoyogi, brought a powerful grimoire called the Dark Oath to Itogami Island. She intended to transform it into a realm without powers, without the supernatural—no magic, no sorcery, no demonkind."
"She failed. Natsuki Minamiya, the 'Witch of the Void,' stopped her and imprisoned her in the Prison Barrier for eternity."
"But LCO wanted her freed—and wanted the Dark Oath back. They used her biological data to create a clone, a witch capable of breaking the Prison Barrier's seal."
Kaiser's eyes bored into her.
"That witch is you—Aya Tokoyogi's daughter, Yuuma Tokoyogi."
Yuuma was an artificial witch, an artificial lifeform, born already six years old.
Meeting Kojou and Nagisa had been pure chance. She'd simply gone out one day, met them playing nearby, and became their friend.
They never knew her origins—never knew she was a witch. They just played together until four years ago, when the incident on Gozo Island happened and Nagisa was sent to Itogami for treatment.
"At that time, Kojou was a genuine ordinary human—still pretty much is, honestly—and had never been involved in any incidents.
"Nagisa was special, yes—an excellent spirit medium and spirit medium—but to you and LCO, she held no value.
"LCO only cares about grimoires. You only wanted to save your mother. You had no reason back then to target either Kojou or Nagisa, let alone deliberately become their friend."
That was why Kaiser said he believed her. Even without knowing the original story, the logic was clear.
"But now… it's different, isn't it?"
Kaiser's gaze was like it could see straight through her.
Yuuma fell silent again—then gave a resigned, almost self-mocking smile.
"You're right. It's different now."
"Because Nagisa is the vessel of the Fourth Primogenitor, carrying its power inside her."
"And I need that power."
Her goal was to free her mother from the Prison Barrier.
But the Barrier was in another dimension—hidden somewhere within Itogami Island, yet in a separate space no one could pinpoint, much less enter.
To locate it and break its seal, Yuuma would have to disrupt the island's spatial fabric.
That was no simple feat.
Spatial interference was rare and difficult—even high-level magi struggled with it. Only a witch like Natsuki Minamiya, specializing in spatial control magic, could manage it easily.
Fortunately, Yuuma was exactly that type of witch. She could twist space with ease.
But distorting all of Itogami Island's space at once would require an enormous amount of magical power—far beyond what any witch could provide alone.
So she'd set her sights on Nagisa… or rather, the Fourth Primogenitor.
"With magical power rivaling a dragon vein, the Fourth Primogenitor's strength would give me enough to warp the entire island's space."
"So I need Nagisa's body—to take the Fourth Primogenitor's power within it."
Her plan wasn't to swap bodies, but to exchange senses—linking their nervous systems through spatial distortion so she could control Nagisa's body while Nagisa would control hers.
This required weaving countless nerve connections through twisted space—something only a witch of her kind could do.
"I only need the power inside her. I have no intention of hurting her," Yuuma said, looking at Kaiser. "Don't stop me, King of Beasts."
It was clear she didn't want him as an enemy.
An ordinary agent wouldn't have fazed her. But this man—
The host of Leviathan, ruler of countless mythical beasts, someone who could defeat Dimitrie Vattler with ease—was another matter entirely.
Even if she succeeded in taking Nagisa's body, even with the Fourth Primogenitor's power, she couldn't be sure she could win against him.
Kaiser's expression didn't change.
"I don't know if you're truly ignorant or just pretending. But let me remind you—"
"Even setting aside whether Nagisa can control the Fourth Primogenitor's power herself… even if you had her body, could you make Avrora lend it to you? And if you could—would you really use it recklessly?"
"Nagisa isn't the Fourth Primogenitor. She's not even a vampire—just a human spirit medium. The true Fourth Primogenitor is dead. Only its soul and power remain, coexisting with her."
"If you push that power too far, her body will give out. Even if it holds together, using the beasts will drain her life—shortening her lifespan."
Kaiser's eyes locked on hers.
"Knowing that… are you still planning to do this?"
Yuuma was silent. For the third time.
The oppressive atmosphere pressed in, her Guardian twitching restlessly.
Finally, she gave a bitter smile.
"I'm a witch. The price for my contract, for my power, is freeing my mother from the Prison Barrier."
If she defied that purpose, her Guardian would behead her on the spot.
So even knowing it would hurt Nagisa, she had no choice but to try.
"I see." Kaiser nodded, unsurprised.
Then—
"I'll stop you."
The moment the words left him, Yuuma's Guardian surged forward, unleashing its vicious magic.