Illya's sudden call-out had been brutal. Had Kiyohime been fully aware of her feelings for Su Mo, she probably wouldn't have minded being found out. She might've even clung to him right then and there. But as things stood, she still bore a strong sense of guilt. After all, she had come to assist Sakura. That was her whole purpose! To now cling to Su Mo so shamelessly… she just couldn't do it. Eventually, Kiyohime dispelled her spirit form and reappeared.
Under Illya's knowing gaze—clearly expecting this outcome—Kiyohime covered her face in embarrassment and scurried out of the room.
Once she was gone, Su Mo looked down at the little girl still holding his hand and finally asked, "Illya, what was that 'small wish' you mentioned earlier? If I'm not mistaken, that's the real reason you came back here, isn't it?"
After their earlier conversation, Su Mo had thought it through. Whether it was the Einzbern family, divine spirit summoning techniques, or the Saint Graph manipulation methods—it didn't make sense for any of those to warrant a direct trip back in time.
Once he won the Holy Grail War and obtained the Third Magic, the Einzbern family would naturally submit. As for the summoning and Graph manipulation techniques, they weren't urgent—time flowed differently here compared to the Mist Realm, after all. There was no reason to rush anything.
And judging from the handwritten tome, it seemed less like something his future self had painstakingly prepared as a crucial tool, and more like a casual note he'd tossed Illya's way after realizing she wanted to come back. It was more like a keepsake or a souvenir than an essential item. Which only reinforced Su Mo's conclusion: her real reason had nothing to do with magic or family.
"Hehe… I knew I couldn't hide anything from you, Papa." Illya scratched her cheek shyly, a little embarrassed but also pleased. Even in his youth, her father was still sharp.
"Alright then, what's the real reason?" Su Mo pressed, genuinely curious. He'd considered many possibilities, but nothing really fit—so he decided to hear it directly from her.
Illya fidgeted for a moment before lowering her head and speaking softly. "Papa… I want a little sister…"
"…What?"
Su Mo froze for a second. "You came all this way… just to remind me to give you a little sister?"
"Is that… even something you can request?"
Then his thoughts turned technical. Wait, since Irisviel is a homunculus, if they cloned the embryo as twins… it might actually be doable. It felt ridiculous at first, but the more he thought about it, the more feasible it seemed. As he started to calculate whether it was viable, Illya frantically waved her hands. "No, no! That's not what I meant!"
"If Papa and Mama Irisviel have another child, that's no good—it could trigger a temporal paradox!" She explained in more detail. In her original timeline, Irisviel had only ever given birth to her. That shouldn't be changed.
"Then what? You want me to have one with someone else?" Su Mo raised a brow. "Can Servants even get pregnant…?"
Well, if they were given proper physical forms, perhaps.
Hearing him veer into these strange hypotheticals, Illya shook her head again, blushing furiously.
"No, Papa! That's not it either! I meant…" She clenched her fists, her cheeks glowing red.
"I want to make a little sister with Papa!" Su Mo stared at her in stunned silence.
Though, to his credit, not completely stunned. It's normal for a little girl to be attached to her father, but…
This wasn't right. At all.
As he struggled to find the right words to address her phrasing, one question echoed in his mind: Did I… raise her wrong? Was this one of those "My daughter's daughter is still my daughter" kind of problems?
Thankfully, Illya quickly realized how her words sounded and frantically waved her arms.
"Wait, wait! That's not what I meant!"
"I remember Papa once told me that there was another possibility within me… and if we activated it at the time of my birth, I'd be able to have a little sister later on."
"But it had to be set up during my birth, using a specific ritual… and only Papa could do it! That's why I came back—to ask you to prepare everything in advance."
"That way, when I return to my own timeline, I can 'pop!' have a little sister. Since the creation needs both me and Papa's involvement, that's what I meant by 'making' a little sister!" Her explanation was frantic and a little messy, but she got the message across.
"Ah, I get it now. You mean Chloe," Su Mo finally said with a wry smile.
Though her words were all over the place, Su Mo understood immediately. The "sister" Illya wanted was none other than the alternate personality from the Magical Girl Illya timeline—Chloe von Einzbern, or as she was affectionately known, Kuro.
Kuro was a split-off version of Illya's self—an alternate possibility that took shape under specific conditions. If the Illya standing before him had been born into a warm, loving home with her parents by her side, then she was the product of love and miracles. By contrast, Kuro represented the hidden side—the repressed feelings and discarded fragments.
But in this timeline, Illya was the daughter of Su Mo and Irisviel. She lived a peaceful, carefree life, untouched by the horrors of the Holy Grail War. As such, she had naturally grown up into the bright and sweet Magical Girl Illya type. The problem was, with all the darkness and danger having been handled by Su Mo alone, there hadn't been any justification for Kuro to exist. Not naturally.
If Illya wanted her "sister" to be born, the ritual needed to be carried out at the moment of her birth—embedding the possibility into her from the very beginning. The two would then co-exist for ten years, and the second self would slowly grow, shaped by Illya's experiences and knowledge.
When the time came, bam, Kuro would be born.
So Illya's real reason for traveling back through time… was to make sure Su Mo remembered to plant that seed. When she returned to her own timeline, that potential could then blossom into her "little sister."
In other words—this was the so-called "Papa and Illya together making a little sister."
Since Kuro would only physically manifest after Illya returned to her own time, the timeline remained paradox-free. Having pieced it all together, Su Mo couldn't help rubbing his temples.
"All this… just to make sure your sister gets born?" he muttered. "Was my future self just… absurdly strong, or just really bored?"
At first, he'd assumed there was some vital message his future self had wanted to pass on. But now it looked like the entire reason was simply that Illya had asked for a little sister—and like a doting father sending his daughter on a school trip, Future Su Mo had casually flung her ten years into the past.
Seriously… what kind of parenting is this?
"Hehe~ Papa's the strongest! You're always amazing!" Illya said proudly, full of admiration.
"You little flatterer. Fine, I've heard your wish loud and clear. No problem," Su Mo said, chuckling as he gently pinched her nose. It was just a little request from his daughter, after all. All he needed to do… was plant one small seed ahead of time. The thought of being able to gain another daughter in the future was far too good an opportunity for Su Mo to pass up.
"Yay! I knew Papa was the best!" Illya beamed, happily hugging Su Mo tight. She hadn't expected things to go so smoothly—just like that, her little wish was granted. As expected… Papa is amazing!
...
...
The next morning, Su Mo rose early as usual and went outside to train swordsmanship with Okita Souji. Sakura and Illya, still just children, were both fast asleep, unwilling to leave their warm beds. Meanwhile, Kiyohime was preparing breakfast in the kitchen—and Irisviel, naturally, was "helping" in her own way.
"One Step—Swifter than Sound!"
"Two Steps—Infinite Suffering!"
"Three Steps—The Absolute Sword!"
"Lightless Three Stage Thrust!"
The flash of a sword lanced forward, piercing clean through the trunk of a tree in the courtyard. On closer inspection, it wasn't so much that the tree had been cut—rather, the strike had caused a distortion in reality itself. There weren't even splinters left behind at the point of impact.
"Master, you're incredible! You've already mastered my secret technique!" Okita, watching from the side, was visibly impressed by how perfectly Su Mo had replicated her moves. It had barely been any time at all, and yet he had already learned everything—even the [Lightless Three Stage Thrust], the pinnacle of her swordsmanship.
"At this rate… I don't think I have anything left to teach you," she said, her tone laced with a hint of melancholy.
......
Was she… going to be out of a job now?
"Then just create new techniques," Su Mo said with a chuckle, sheathing his sword. He looked over at the dejected swordswoman and spoke again, "If I remember right, in history, Okita, you died young. You were a prodigy of the blade, famous at a young age—but that was far from your limit."
Okita Souji was a tragic genius, someone who perished too soon. While her [Lightless Three Stage Thrust] was a technique refined to the point of nearly becoming a Noble Phantasm, it was still something she had developed in her youth.
"If you grew that much after only a few years of training, imagine how strong you'd become if you kept pushing forward on the path of the sword. Even now, there's no doubt you could surpass your former self."
In her mortal life, Okita had been held back by a frail body that prevented her from reaching her true peak. But now, as a Servant, those constraints no longer existed. If she continued her training, it stood to reason that she could far exceed what she had once been.
But Okita shook her head. "But Master, as a Servant… no matter how hard I train, I can't grow stronger."
The moment a Heroic Spirit was summoned, their abilities were fixed. Even if she continued to polish her skills, it wouldn't reflect in her parameters. That was simply how Servants worked.
Su Mo, however, rejected that limitation.
"Not necessarily," he said calmly. "Even Servants can grow stronger. Once I obtain the Third Magic, I'll be able to modify your Saint Graph directly." After all, Okita held the potential to become Devil Saber Souji. With the power of the Third Magic, that potential could be realized. "So don't lose heart. I believe in your potential." He smiled gently at her, offering sincere encouragement.
"Master!" Overcome with emotion, Okita threw herself into his arms, deeply touched by his words and his faith in her. Su Mo ruffled her hair, then looked out toward the horizon. "That's enough training for today. I've got a good grasp on the situation with this Holy Grail War now."
"Tonight… it ends."
Having gained enough intel from Illya, Su Mo had no intention of dragging things out any longer. Most Saint Graph manipulation required the Third Magic anyway—so wrapping up the Holy Grail War ahead of time was simply the logical move.
"Tonight is the final battle."