After some time, Sakura and Rin finally finished absorbing all the cosmic energy in their bodies. Since Sakura had previously used chat group points to enhance her body, she was able to absorb much more energy than Rin.
While Rin had just stepped into the early stages of Third Level, Sakura had already reached the middle stages of Third Level.
The two of them opened their eyes one after the other, and as they clenched their fists, they could clearly feel the explosive power coursing through their bodies.
"Ah… Eriri, I've reached Third Level, Fourth Stage!" Sakura exclaimed in the chat group as she saw her power level. She couldn't believe that her strength had surpassed most of the chat group members in less than an hour. This must be the benefit of having a powerful mentor.
"Very impressive," Eriri said as she patted Sakura's head. The progress of both sisters had exceeded her expectations. The other members who had evolved previously, except for Arifureta, had only reached Second Level, Ninth Stage, while these two had already stepped into Third Level, a significant difference.
At that moment, Rin's excited voice came from the side: "I can feel how powerful I've become! This is amazing! I need to tell Father!"
As a daddy's girl, the first thing Rin thought of after sensing her newfound power was to tell her father. However, this went against Eriri's plans.
"Stop!"
Seeing Rin about to jump off the bed, Eriri swiftly pressed down on her head, holding her in place.
Feeling the pressure on her head, Rin was utterly bewildered. She found herself powerless against Eriri's delicate hand and began to doubt whether the strength she felt earlier was real.
"Eriri, what are you doing? Let me go!" Rin said in a cute, frustrated voice. By now, her initial reservations toward Eriri had faded, and she even started to have a good impression of her.
"You can't tell anyone about your strength—at least not yet."
Eriri still wanted to see the exciting events unfold later. If Tokiomi Tohsaka, their father, learned about their powers too soon, he would undoubtedly exploit their strength to win the Holy Grail, given his ambitions and desire for the Grail. That would spoil the fun.
Sakura readily agreed with Eriri's request. Ever since she had overheard Tokiomi's plan to adopt her out to the Matou family, her fondness for her father had diminished. While she hadn't cut ties with him, their relationship wasn't as close as before.
Only Rin seemed resistant to Eriri's demand. "Why? Can't I at least tell Father?"
"Absolutely not. You need to act as though nothing has changed. When the time is right, you can tell anyone you want. If you reveal it too early, I'll take your powers back," Eriri said with a sly grin. Though it was a mischievous smile, it somehow added to her beauty.
Even so, Eriri's words struck fear into Rin. She knew that her newfound strength came from Eriri, so she didn't doubt that Eriri could take it away.
With no other choice, Rin reluctantly agreed. "Fine, I understand."
"Good girl, Rin-chan," Eriri said as she released Rin's head. Rin, now free, no longer had any thoughts of running to her father.
As their strength had increased, both Sakura and Rin now faced a common problem—controlling their newfound power.
Going from ordinary humans to national-level powerhouses in such a short time, the sudden surge of strength wasn't something they could easily manage, especially since they were still children.
Even Eriri, back when her body first awakened, had taken a long time to adjust to her new strength. As for the other chat group members like Megumi Kato, who had mainly enhanced their elemental powers, their physical strength didn't come close to Sakura and Rin's levels.
For example, when Sakura got off the bed, she accidentally exerted too much force, causing the entire bed to collapse. Meanwhile, Rin fell through the floor and into the room below, creating a large hole in the process.
If Eriri hadn't quickly isolated the two rooms with a barrier, the sound of destruction would have alerted everyone in the Tohsaka household, making it impossible to avoid suspicion.
"Are you okay, Sister?" Sakura asked nervously, carefully approaching the edge of the hole to look down.
"I'm fine, Sakura. Don't worry. This height is nothing to me," Rin called back from the room below, standing in a crater formed by her fall.
Looking at the dirt walls around her, Rin couldn't help but mutter, "Just how strong is my body now? This is insane…"
She was now afraid to move carelessly, worried that she might cause even more damage to her surroundings.
Sakura, on the other hand, had fared slightly better. Although she hadn't fallen, the floor creaked under her feet, leaving small indentations with each step, which also troubled her.
"Eriri, what should we do? My sister and I can't control our strength. We can't even live normally like this," Sakura asked with a worried expression. Even though she spoke softly, Rin, several meters away, heard her perfectly, thanks to their enhanced senses.
Rin also looked expectantly at Eriri, hoping for a solution.
"That's easy to fix."
Unlike before, when Eriri had no experience adjusting to her powers, she now knew exactly how to help others quickly adapt to their newfound strength, having already overseen the evolution of several people.
The solution was simple: combat training. By fighting, they could learn to control their strength naturally.
"Really? That's great! Eriri, please teach us how to do it!" Rin, lying in the crater, broke into a wide smile. She didn't want to be stuck in her current situation where she couldn't move freely.
"Of course, but first we need to fix the damage you've caused. Otherwise, we'll have a hard time explaining this to others."
"How are we supposed to repair it?" Sakura asked, looking around at the extent of the destruction. The damage was severe enough that calling in a construction crew would be time-consuming. Restoring everything in a short time seemed impossible unless they could turn back time to before the room was destroyed.
Eriri's next move confirmed Sakura's suspicions and left Rin speechless in awe.
Without even approaching, Eriri extended her hand and telekinetically lifted Rin out of the hole, tucking her under her arm. With a casual wave, the scene inside the room began to reverse at an incredible speed.
Sakura and Rin could clearly sense time flowing backward in the room, though they themselves weren't affected. It felt as if they were standing in another dimension.
Within moments, the floor was repaired, and the bed restored, making both rooms look exactly as they had before the incident.
The miraculous scene left Rin speechless for a long time. She finally understood just how powerful Eriri was. The ability to control time like this meant Eriri could never be defeated. Before this, Rin had admired her father above all, but now her respect had shifted to Eriri.
"All fixed. Now let's work on helping you control your strength," Eriri said, snapping the sisters out of their reverie.
Rin, still tucked under Eriri's arm, didn't resist or protest. She obediently let Eriri hold her, which earned her a strange look from Eriri, as this didn't match Rin's usually stubborn personality.
After setting Rin down beside Sakura, Eriri took a few steps back and gestured for them to come at her. "Sakura, Rin-chan, attack me with everything you've got until you can fully control your strength."
The sisters exchanged uncertain glances, then looked around the room, clearly worried about causing more damage.
Reading their thoughts, Eriri smiled. "Go all out. I've placed a protective barrier around the room. No matter how strong you get, you won't damage anything. Didn't you notice the floor hasn't even cracked under your feet?"
"Wow, you're right." With their concerns alleviated, the two sisters began moving around freely, throwing punches and kicks, but all their force was absorbed by the transparent barrier around them.
Under Eriri's guidance, and with no fear of damaging their surroundings, Sakura and Rin exchanged determined looks before rushing at Eriri with wild, uncoordinated attacks.
...
An hour later, Eriri finally called off the sparring session.
After an hour of constant exertion, both Sakura and Rin had gained full control over their newfound strength. They were now truly national-level powerhouses, solidly at Third Level.
With that, Eriri's goal for visiting this world was accomplished. Not only that, but she had gained a new fan.
Throughout the hour-long training session, Rin had grown increasingly obedient toward Eriri. By the end, she was calling Eriri "Onee-chan" with glee, her previous tsundere attitude nowhere to be found.
"With your current strength, you two will be able to easily dominate the Fourth Holy Grail War in about a year. I'm looking forward to seeing you in action."
"What's the Holy Grail War?" The sisters were curious about the unfamiliar term Eriri had mentioned.
So Eriri briefly explained the basics of the Holy Grail War and once again reminded Rin not to reveal her newfound strength to Tokiomi. She didn't need to worry about Sakura, as Eriri trusted her completely.
After dispelling the isolation barrier around the room, Eriri disappeared from their sight, leaving the sisters watching her go with reluctant gazes.
However, Eriri didn't immediately leave the world of Fate/Zero. Instead, she headed to a castle deep within a forest in Germany.
It was four hours later when Eriri finally returned to the world of Saekano.
...
The next morning, Eriri woke up in her new bedroom. Her room was located in the center of the second floor of the villa and was the largest one.
The room's decor and arrangement were almost identical to her previous bedroom, except it was much larger, leaving plenty of space. This meant her collection could expand further, and she was already thinking of filling the wall again.
"Mmm…"
A sleepy mumble came from under the covers, revealing a head of golden hair.
A moment later, the completely nude Arifureta crawled out from under the blanket. The previous night, before Eriri had fallen asleep, Arifureta had snuck into her room with a pillow. After some indescribable events, the two had fallen asleep in each other's arms.
Rubbing her eyes, Arifureta greeted Eriri, "Good morning, Eriri."
"Good morning, Arifureta. You were amazing last night," Eriri replied, patting her head. Arifureta's silky golden hair remained smooth and shiny, despite being slept on all night.
"Hehe, you were amazing too," Arifureta said as she wrapped her arms around Eriri's back, nuzzling her head against Eriri's chest.
The two had thoroughly enjoyed themselves the night before, and even Arifureta seemed to have developed a taste for the experience.
Not wasting much time, the two quickly dressed, freshened up, and headed to the dining room.
...