Return to Chaldea.
This decision—Rozen had certainly made the right call.
With Chaldea's fully equipped facilities and Roman's professional adjustments, Rozen's Magic Circuits were being steadily nourished at a pace far surpassing anything before.
Just as Roman had said: with the current scale of Rozen's Magic Circuits, it was nearly impossible for them to even develop problems. Had Rozen not gone too far with his recklessness this time, they would never have malfunctioned in the first place.
And even with that issue, it was merely a matter of stagnation in operation—not a serious problem. With proper nourishment and adjustment, recovery was not difficult at all.
Of course, it would take a bit of time.
After all, Magic Circuits are tied directly to the soul—tied to life itself. If not treated with care, the consequences to the person could be significant.
Wasn't it in the past that Rozen's circuits were so exceptional that most of his life force was consumed to generate mana, leading to that frail and sickly constitution?
Because of that, Roman gave Rozen plenty of advice.
For example, Roman told Rozen not to rush the recovery of his mana, and instead let his Magic Circuits rest properly. If the circuits continued running while in an overheated state, the cooling process would only take longer.
The best way to cool an engine is, of course, to shut it down. That much is common sense.
Even though Rozen's Magic Circuits were of the autonomous type—able to run and generate mana on their own—Roman still advised him to refrain from manually producing any more, aside from the naturally generated portion, to avoid further increasing the load.
That way, the circuits would have ample time to rest and regenerate, allowing Roman to better fine-tune them.
If Rozen's mana were still at its previous levels, external adjustments would have been even harder to implement.
Thus, Rozen followed Roman's plan and ceased any active operation of his circuits, letting them function on autonomous mode only.
Thanks to that, the recovery of Rozen's Magic Circuits was going very well—but his mana recovery had slowed down compared to before.
Still, that was only temporary.
Once the Magic Circuits fully returned to form, Rozen would only need at most a day and night to restore his mana to peak condition.
With that in mind, Rozen found himself in no rush at all.
However, since the recovery of mana had slowed, he naturally needed to minimize its consumption.
To that end, aside from Mash and Altera, all the other Servants had de-manifested and returned into Rozen's body, reverting to their Beast Vassal forms and slumbering in his bloodstream—lightening his burden.
Mash had originally wanted to do the same, but since they had returned to Chaldea, Rozen felt it would be a bit too much to keep her dormant inside him. So, he allowed her to remain active.
As for Altera, even though her Saint Graph was of Grand-class—which by all rights should consume even more mana to maintain—she had been forged with a Holy Grail, and retained a portion of its power. Thanks to this, she could draw from the Grail's energy within her Saint Graph and remain active without relying on Rozen's supply. Even in combat, she was completely self-sufficient.
In game terms, Altera essentially had the Independent Action skill—at quite a high rank. As long as there were no extreme conditions, she could function independently of Rozen without issue.
This made Altera the only Servant who didn't consume any of Rozen's mana, like the jujutsu-forged Kinu and Gyokuto, who also posed no significant burden.
This even led Mash, for the first time, to seriously consider obtaining a Holy Grail.
Had the Holy Grail not been such a great help to Rozen, this kind-hearted kouhai would surely have been wracked with guilt for being a burden.
Rozen had reassured her once:
"There are other worlds where I have familiars bound by absolute contract. I provide them mana too. One more or less really doesn't make a difference."
With that, Mash was finally able to let go of a bit of her guilt.
What she didn't know, however, was that the current consumption level was just barely at Rozen's limit.
By giving up manual regeneration and relying solely on autonomous generation, the amount of mana his circuits could produce wasn't much. After feeding all his Beast Vassal girls, there was just the slightest surplus left.
If even one more Servant had been present, Rozen's supply would have entered a deficit—and would've been depleted again sooner or later.
Being able to retain just a little surplus was the most ideal condition.
Rozen himself didn't realize that even after supporting so many Servants, the fact that he could still accumulate excess mana solely through autonomous operation of his circuits was absolutely absurd.
After all, for a normal Magus, sustaining even one Servant's consumption was a serious challenge.
In Fuyuki's Holy Grail War, the Masters could afford their Servants' upkeep only because the Holy Grail covered most of the energy cost.
In other words, Rozen alone was covering the full cost for all his Beast Vassals—just with autonomous generation. That alone made him a monster. No wonder Roman found the data on his circuits unbelievable.
And this was with Rozen's circuits still in an impaired state.
Once they fully recovered, their autonomous generation would be even stronger—strong enough to support all his Servants without breaking a sweat.
That would be a Magic Circuit with truly infinite potential.
With the cosmic principle of something-from-nothing—Infinite Chain Reaction—Rozen would never have to worry about mana again.
If one were to say that Rozen's true rise began when he acquired this Magic Circuit, that would not be an exaggeration.
Unfortunately, this time, Rozen had been too reckless.
Forcing himself to forge incomplete Foreign Mana, and opening the Gate that led to the records of countless worlds—just thinking about it made clear how reckless he had been. This was the price he paid.
That said, in return, he had gained access to the power of the Cleansing, which gathered all the knowledge from countless worlds and embodied omniscience and omnipotence.
It was well worth the cost.
Now, Rozen only needed to wait for his Magic Circuits to recover and for the Foreign Mana to finish its sublimation. After that, both Miracle and Cleansing would be wielded as effortlessly as his own limbs.
At that point, Rozen would truly take flight.
Still—like before—it would take time.
But not much time.
Rozen could feel it.
"In another month, the sublimation of Foreign Mana will be complete. The Magic Circuit will recover even sooner."
It was close.
So very close.
Rozen couldn't help but feel excited.
But, as always—life was full of surprises.
Just as Rozen quietly awaited everything's completion, a different piece of news arrived.
"Preparations for the spiritron transfer to the Seventh Singularity are complete."
In other words—the operation to repair the final Singularity could now begin.
When Rozen heard this, he couldn't help but let out a bitter smile.
"Talk about bad timing."