Zepia from a parallel world.
The information from Naoki surprised Sion slightly, but as someone from the Atlas Institute, she was already accustomed to encountering strange phenomena every day. So, the concept of parallel worlds wasn't something she couldn't accept.
"I see... parallel worlds. No wonder the Headmaster said what he did. His words no longer contain any paradox."
"But still, killing your own self from a parallel world—why would the Headmaster come up with such an idea?"
This was something she couldn't understand.
Magus, by nature, were selfish. They only cared about their own interests. Beyond that, they were indifferent. Even if the world were to collapse, a typical magus would continue their research, hoping to reach the Root before the end came.
That was the mindset of most Magus.
But Magus from the Atlas Institute were slightly different.
"Perhaps in his calculations, the actions of his parallel-world self could lead to the destruction of this world."
That was Naoki's thought.
Magus of the Atlas Institute didn't pursue the Root. Instead, they pursued [saving the world]. This was because their first Headmaster had proven that, in the distant future, the world would inevitably be destroyed. Therefore, to avoid such a fate, Atlas Magus continuously carried out their own form of [world salvation], endlessly repeating the cycle of destroying and creating weapons.
Zepia, as the Headmaster of the Atlas Institute and a Dead Apostle who had lived for hundreds of years, likely sensed anomalies between worlds and predicted his other self's arrival. And upon determining that the actions of his alternate self might bring about the world's destruction, he decided to have Sion destroy that version of himself.
"Saving the world... That's the only possible explanation."
Sion wore an expression of deep understanding.
It should be noted that, at the Atlas Institute, every second, Magus were predicting new forms of world destruction. [Saving the world] was merely a routine, an endless cycle carried out within the Institute. If someone were to declare, "I will definitely save the world!" at the Atlas Institute, they'd likely receive nothing but scornful stares.
It wasn't mockery—it was anger. If you have time to boast, you should instead go do research and find a way to prevent the world's destruction faster.
"But it's still strange. The world's destruction that he himself foresaw—he usually resolves it himself. Why suddenly entrust the future he predicted to me? My adoptive father, who never cared about anything, would never depend on someone else."
Every predicted world destruction by Atlas Magus was different. Thus, they also believed only they could prevent the specific apocalypse they foresaw. As Headmaster, Zepia thought the same.
Yet this time, he entrusted his own prediction to Sion.
"Even though there's no way I could fight an Ancestor... or could it be because of this?"
As if suddenly realizing something, Sion murmured while looking at Naoki: "Is it because of you?"
"Me? Why me?"
"Though this is just a wild guess, the Headmaster told me to come here... the reason [meeting Naoki] probably accounted for sixty percent of his motives. After all, he seems to really like you. But why would he want me to meet you?"
"The Holy Sword Heir." Ayaka suddenly said. "Could it be because Naoki is the Holy Sword Heir?"
Sion frowned. "Holy Sword Heir? What's that?"
"Just as the name suggests."
Naoki pretended to grip something, then materialized the Sword Excalibur and explained: "This is the Star's Holy Sword, forged by fairies to defeat enemies from beyond trying to destroy the star. If I say this is the Excalibur once wielded by King Arthur, you'd probably be more familiar with it, right?"
"I am its current owner, and have been chosen by the Counter Force as the third Star Holy Sword Heir. How should I put it... I'm someone who sees [saving the world] as a mission to fulfill."
In reality, Naoki had saved the world countless times. One could even say he saved it every single day. To prevent the descent of the Sixth Beast, he fought desperately every day against the two Root Princesses.
Sion didn't fully understand what Naoki was saying, but seeing the Holy Sword in his hand, she instinctively felt he wasn't lying. A voice deep within her heart kept telling her that the man before her truly was the Holy Sword Heir capable of saving the world.
Could it be that Zepia knew this, and that's why he told me to meet him? For Atlas Magus whose goal was world salvation, the Star Holy Sword Heir was essentially the most desired ally.
"Hmm, if this hypothesis is correct, the Headmaster's intentions make perfect sense. Even if the truth isn't exactly this, for now I'll accept it as such."
Standing up, Sion smiled and extended her hand to Naoki: "Let's properly introduce ourselves again. I'm Sion—Sion Eltnam Atlasia, an alchemist. I'll probably have many things to ask of you in the future, Holy Sword Heir who saves the world."
(Not 'probably,' but definitely.)
During the freezing of human history, Sion was the behind-the-scenes hero who helped Chaldea reclaim the world. If she hadn't prepared New Chaldea in the Sea of Wandering and waited, Chaldea in the future might have reached a dead end.
And as the current head of Chaldea's operations, Naoki would definitely meet Sion again in the future.
"I'm Natsukawa Naoki. Just call me Natsukawa or Naoki. No need to be so formal."
Naoki took Sion's hand and smiled at her: "For me, there's no problem. As long as it's within my ability, I'll do my best to help you. I'm glad to be working with you, Sion."
(So dazzling!)
Seeing his bright smile, Sion suddenly felt as if she were wrapped in the warm midday sun in the middle of winter.
Smiling at her so warmly... this is unfair! His attack power is too high! Has this person never tried to hold back at all?
Seeing Sion's cheeks slightly flush, of the three others present, only Arcueid remained oblivious. Touko and Ayaka, however, were both slightly taken aback.
After a pause, Touko somehow pulled out a camera from nowhere and quickly snapped a photo of Naoki and Sion, still holding hands.
*CLICK!*
The sound startled both of them. Naoki stared at Touko, confused: "Touko, what are you doing? Suddenly taking a photo?"
"Nothing. I just took a picture of someone cheating, planning to send it to the uncaring magus who ignores his home, to let him know that while he's out playing, his entire household has already been completely stolen away."