"My... my brethren are now in your blood...?" Avrora was the first to react, becoming a bit flustered.
No, it wasn't just Avrora; the others also began to feel uneasy.
"Vampire's beast vessels are nurtured in human blood?"
"Is this... Is this okay? Are you alright, Nichiyo?"
Kojou and Nagisa were both surprised and anxious.
You see, vassal beasts come from a magical aggregation in another world, carrying their own will. Although they can be nurtured in blood and controlled by humans, only vampires can use them. Because vassal beasts rapidly drain the life force of their hosts when materialized.
If summoned by ordinary humans, their life force would be drained quickly. Even the long-lived species, who can survive for ages, wouldn't last long if they recklessly used vassal beasts.
Only vampires, who are immortal, have unlimited life force, so even the weakest vampire has the qualifications to summon vassal beasts. The difference lies in whether they can successfully summon or control them. If successful, they can nurture vassal beasts in their blood; if not, they degrade into Nosferata—it's that simple.
In this situation, Rozen actually claimed that his blood was nurturing beast vassals, specifically the Catastrophe-class beast vassals of the Fourth Primogenitor, a total of nine.
How could people not be anxious about such a thing?
"Don't worry."
Seeing Avrora, Nagisa, and Kojou all getting flustered, Rozen hurriedly spoke up.
"They're just residing in my blood for now. As long as I don't summon them, they won't drain my life force. You all know this, right? They only absorb the host's life force upon materialization."
Upon hearing this, everyone felt a bit relieved.
Only Natsuki, however, picked up on another piece of information in Rozen's words.
"As long as you don't summon them?" Natsuki calmly said. "In other words, if you're willing, you can summon them anytime, right?"
Natsuki's astute observation made Rozen scratch his cheek.
"Well, at least that's how I feel."
Rozen admitted.
That's the current situation.
Originally, when Rozen forcibly pulled the original out of Nagisa's body, the nine vassal beasts controlled by the original entered Rozen's body together.
According to that trend, the nine vassal beasts should have been sealed along with the original.
However, when Rozen woke up this morning, he found that the nine beast vassals controlled by the original had not been sealed.
The reason is simple.
"They willingly submitted and are willing to accept my control, losing their resistance to me. Therefore, the seal automatically filtered out their presence, allowing them to reside in my blood. I only just discovered their existence and gained control over them."
Rozen voluntarily explained the process of events.
In other words...
"In order to avoid being sealed, those beast vassals acknowledged you as their master?" Kojou said, somewhat enlightened.
"What clever beast vessels, they even know how to escape sealing in this way."
Nagisa looked somewhat admiring.
Only Avrora suddenly shook her head while everyone else realized what was happening.
"I... I don't think it's like that."
Avrora hesitated and spoke uncertainly.
"I believe that my brethren didn't willingly submit just to protect themselves."
Avrora's statement was full of certainty.
Avrora herself has a beast vassal of the Fourth Primogenitor inside her, so her words are representative.
This is what Avrora said.
"They will acknowledge allegiance not so much to escape sealing but merely to recognize Nichiyo's qualification."
What qualification?
Naturally, it's the qualification as the master.
That's the reason why the vassal beasts willingly submitted.
"They acknowledge your talent and strength by being able to seal the Fourth Primogenitor's original soul. Additionally, the nine Matrices absorbed by the original were part of the beast vessels, and since beast vessels carry their will, upon defeating the original, they chose to submit to you."
Avrora said in a somewhat complicated tone.
But isn't this probably the truth?
The purpose of the Matrices is to serve as carriers for the beast vessels, so they are part of the beast vessels themselves. When their existence disperses, their will, spirit, and blood memories become part of the beast vessels.
In other words, the nine beast vassals possess the will and memories of the nine Matrices, as if they were their own selves.
As a result, the Matrices were created to seal the original. The original regarded them as useless puppets, so it's natural for the beast vessels to harbor some resistance towards it.
If the original's power weren't so strong and if it didn't have considerable control over its beast vessels, perhaps the beast vessels would have revolted.
Thus, when the original was sealed by Rozen, the nine vassal beasts, freed from its control, recognized Rozen's abilities, willingly submitted, transferred their control to Rozen, and resided in his blood.
"Furthermore, they also fear your follower..."
Avrora said timidly, allowing Rozen to understand.
Presumably, those nine beast vassals were also frightened by Altera power, right?
Therefore, upon learning that Altera was Rozen's follower and that Rozen was Altera's master, the nine beast vassals promptly acknowledged Rozen's authority.
One reason after another, Rozen obtained the acknowledgment and submission of the nine strongest beast vassals, allowing them to reside in his blood.
Now, Rozen can feel that he can summon these nine beast vassals at any time.
However...
"Even if the brethren submit to you, you are ultimately a human. If you summon them, your life force will inevitably be drained. I believe this is not a wise decision."
Avrora rarely expressed her thoughts, though her expression remained timid, it was convincing.
However, Avrora didn't know that since Rozen could use the seal inside him to supply the magic power needed for his familiars, he could naturally use the seal inside him to supply the life force needed for the vassal beasts. Even generating magic power in the future, Rozen wouldn't need to convert his own life force; he could directly extract the endless life force from the seal, which was Rozen's arrangement and setting for his own seal.
Given this, the life force needed for the beast vassals isn't a problem.
The problem is the magic power needed to summon them, which Rozen really can't afford.
Without releasing the seal, even with Rozen's magic power, even if he could summon the beast vassals, their power would inevitably be greatly reduced, right?
At least, they wouldn't be able to exert strategic-level power anymore; the power of the beast vassals summoned by Rozen would probably only be tactical, comparable to second and third generations, not reaching the level of Primogenitors.
But this also means that Rozen would be able to exert the capabilities equivalent to those of second and third generations of vampires.
Moreover, since Rozen can release the seal, even the first seal, he would have more than twice the magic power of the Fourth Primogenitor.
By then, the vassal beasts would not only regain their original power but also become stronger.
(Perhaps, this is also the reason they actively submitted, that's also possible.)
That's what Rozen thought.
This is also an unexpected benefit.