At the heart of the Atlas Institute lay a vast underground cavern, large enough to rival a city, with a simulated blue sky overhead.
Everything necessary for human life was present here. Even with the artificial sky, the apprentices of the Atlas Institute were able to maintain their physical and mental well-being and continue their research uninterrupted.
Towering beneath this sky stood the Institute's greatest record-keeping device—the Pseudo-Spiritron Calculation Engine, Tri-Hermes.
It was also the prototype for Chaldea's Spiritron Calculation Engine, Trismegistus.
"Hermes…" Gray murmured, recognizing the name.
The giant bird that had fought Shiomi and Morgan beneath the Blackmore Village graveyard had also borne that name.
After leading the group to the base of the obelisk, Holmes restored access to the facility. But with the Atlas Institute now a ruin, there was no one left to contact. They could only proceed without permission.
"But... how are the machines here still running, even after being buried beneath the desert?" Mash asked curiously.
"The answer's quite simple," Holmes replied. "This is the Atlas Institute as it existed in 2016."
"I've heard that both the Atlas Institute and the Wandering Sea exist independently of fixed time coordinates," Sakura explained. "No matter what era you visit, you always arrive at a fixed point in their timeline. But only the Magi here know why."
"Miss Sakura, you're quite familiar with the issues surrounding the Mage's Association," Holmes said with a hearty laugh. "As I mentioned on the way here, we have several matters to investigate. One of them involves your father—Tenkei Shiomi, the Magus."
During their journey, Holmes had pointed out Shiomi's peculiarity. After Sakura gave her thoughtful consent, he shared the nature of his investigation and the secrets he was pursuing.
"However, before we dig into Tenkei Shiomi, there's something else I must look into." Holmes operated the equipment beneath the obelisk. Though he wasn't an Atlas Institute Magus and couldn't access every record, the device itself documented all phenomena.
"As Miss Sakura noted, the winners of the Fifth Holy Grail War were Marisbury and Caster—the King of Magecraft. But public records list Saber as the victor."
Sakura knew something about that discrepancy.
After the war, Marisbury had sought out Shiomi. Since silencing someone who knew the truth wasn't an option, the former director opted for cooperation instead.
As for the reason behind the cover-up, Marisbury had claimed that a clear victory in the Holy Grail War would draw too much attention to the Department of Astromancy.
Through monetary arrangements, he offered Sakura generous compensation to take on the title of victor, downplaying the war's actual outcome as much as possible.
Sakura had been reluctant. After all, it felt like a betrayal of the bond she and Saber had shared, fighting side by side to the very end.
But Shiomi had persuaded her to accept.
He seemed to have his own reasons. Sakura never asked—and didn't feel the need to. When the time came, she believed she would understand.
"But that's just a footnote," Holmes continued. "The real issue is that a year after the Fifth Holy Grail War ended, Romani Archaman, at the age of twenty-two, became the head of Chaldea's medical department. And yet, there's no record of any activity from him prior to 2004. It's as if he simply appeared out of nowhere that year."
"Does Dr. Roman's background have something to do with Professor Shiomi?" Ritsuka asked, puzzled.
"That's just my hypothesis," Holmes replied. "But I suspect that the reason Miss Sakura's father agreed to Marisbury's deal may be related to Romani Archaman. In other words, Tenkei Shiomi might have already known Romani—or rather, known who he truly was."
Sakura tried hard to recall her memories from before 2004. "But as far as I remember, my father never mentioned anything about Dr. Roman before that…"
"Now that you mention it, I remember something from one of Professor Shiomi's lectures at Chaldea," Ritsuka said, rubbing her chin. "After Dr. Roman chimed in with a joke, the professor said something like—"
'Hearing you call me "sensei" in a Magecraft class only sounds like sarcasm,' right, Senpai?" Mash added, recalling it clearly. "But Dr. Roman didn't even have the qualifications of a Magus. He didn't have Magic Circuits at all."
Gray frowned slightly. "Professor Shiomi isn't the type to look down on someone just because they're not a Magus. On the contrary, he usually mocked those from prestigious, long-standing Magus Families."
"Oh?" Holmes raised an eyebrow. "Even jokes tend to carry a kernel of truth. For him to say something like that to Romani—on a literal level—it almost implies that Romani's skill as a Magus was far superior to his own. Would someone without any magical aptitude ever earn such an evaluation?"
It was still just speculation, but Holmes's line of thought made them realize something—Shiomi and Dr. Roman were more familiar with each other than anyone had thought, and not just within Chaldea.
Gray then remembered the first time she had set foot in Fuyuki. She and Caren had gone out with Shiomi and happened to run into Dr. Roman on the way.
At the time, Shiomi had simply said he was an old acquaintance.
Gray lowered her head slightly. It might be a clue. But rather than keep speculating here with a stranger—no matter how familiar he seemed from the detective novels—perhaps it was best to ask directly.
After all, their original reason for coming here was to investigate why Add had gone silent and to identify the true name of the Servant who had lent Mash her strength.
Between trusting the people she knew and speculating with new allies, Gray chose the former.
"Even if my father has known Dr. Romani for a long time, so what?" Sakura echoed that trust without hesitation.
Sensing the dissatisfaction in her voice, Holmes offered a quiet apology.
"I meant no offense. I'm not asking you to doubt your companions—only to consider a fact: Tenkei Shiomi is shrouded in a mystery no less profound than the incineration of humanity itself. Even the King of Magecraft couldn't see through him. That's why, when Shiomi first stepped into a Singularity, the King took advantage of a moment of 'leisure' to appear and eliminate him with overwhelming force—eliminating a potential threat."
With that, Holmes turned to operate Hermes and began searching for new data.
"According to what the King of Magecraft said at the Fourth Singularity, the incineration of human order has already been completed. He's now preparing for the next phase—and Tenkei Shiomi's existence is undoubtedly an obstacle to that."