Mash Kyrielight.
The most familiar stranger to Naoki in Chaldea.
An artificial lifeform created in 2000 as the foundation for the Servant fusion project.
In the future, after the Human Order Incineration occurs, she would become Chaldea's sole combat force, working alongside humanity's last Master to restore the Human Order. The girl who inherited the power of the Servant Galahad.
Of course, at this moment, she had not yet fused with a Servant and was still a young child, around seven years old.
"Let me introduce you. This is Mash Kyrielight. The patient Marisbury entrusted entirely to me—what kind of patient, Natsukawa, you already know without me saying, right?" Roman said to the two of them before turning to the young Mash. "Mash, these are my acquaintances, Naoki and Gray. Say hello."
"Mr. Natsukawa and Miss Gray? Nice to meet you, I'm Mash Kyrielight."
Mash seemed very shy. When speaking, she avoided eye contact with Naoki and Gray, leaning against Roman as if she relied heavily on him.
Seeing Mash like this, Naoki took a deep breath. "Phew~ So this is the child you want me to give Fairy protection to?"
"Yes. She's a test-tube baby created for the Servant fusion experiment. Her physical condition is very fragile. Without this isolation room, she'd get sick easily in the outside world. Her mental state is also immature." Roman explained. "Marisbury doesn't want anyone to know of her existence, so he secretly entrusted her to me. He hopes I can adjust her physical condition so she can move freely. With your protection, this process should speed up…"
Though he said that, it wasn't Roman's original intention. He simply hoped Naoki's protection could improve Mash's physical condition slightly. As a doctor, that was a reasonable thought.
"Big Brother…"
Gray suddenly tugged at Naoki's sleeve. "This child… she's a bit like me when I was young…"
"Yeah, I know."
Mash was created for the Servant fusion project, while Gray was made to revive King Arthur—both were vessels crafted for specific purposes.
That's why Gray felt empathy. After all, the girl before her was, in a sense, another version of herself. Fortunately, Gray had been rescued when she was very young. Her brother had taken her from that remote village, saving her from her fate as a vessel.
"Can Big Brother help her?"
"I never said I wouldn't."
Patting Gray's head, Naoki looked at Roman. "Can I go in? To grant the protection, I need physical contact."
"You can, but you'll need to be sterilized. Mash's immune system is very weak."
"Leave it to me. Gray, you come in too."
"Okay."
After being sterilized with Roman's help, Naoki and Gray entered Mash's isolation room.
Seeing the two of them enter, Mash visibly showed a hint of fear—strangers she didn't know, but they were Doctor Roman's acquaintances, so they shouldn't be bad people. Just by looking at her expression, Naoki could guess what she was thinking.
Children's thoughts were so easy to read.
"Let me go first, Big Brother."
Gray crouched in front of Mash and extended her hand. "Hi, Mash. I'm Gray. Can we be friends?"
"Friends?" Mash looked at Gray's outstretched hand, confused. "What are friends?"
"They're people who, like Doctor Roman, can often come to keep you company and look out for you."
"Like the doctor?"
Mash glanced at Roman, and seeing his smiling expression, she hesitantly reached out but quickly pulled her hand back—she didn't trust strangers she'd just met.
"Mash."
Now it was Naoki's turn to crouch. He opened his palm, and a small droplet of water formed, slowly transforming into a flying bird. Then it shifted into a kitten, a puppy, a pony… various shapes appeared one after another in Naoki's hand.
Children naturally love to play, and Mash was no exception. Though extremely shy, she couldn't resist her curiosity about this novelty. "W-what's this?"
"A little Magecraft. Think of it as a gift for our first meeting, little princess." Naoki smiled. "I'm Natsukawa Naoki. Nice to meet you, Mash."
"Natsukawa… Yes, hello, Mr. Natsukawa. And… Miss Gray."
"You can call us Big Brother and Big Sister."
"Big Brother? Big Sister?"
Mash, not yet understanding those terms, tilted her head. Meanwhile, from outside, Roman's anxious voice came through the intercom. "Don't teach Mash unnecessary things, Natsukawa! The protection, give her the protection!"
"I know, I know. Don't rush me."
Waving his hand, Naoki held the water orb in his palm toward Mash. Accompanied by a faint blue light, the orb seemed to transform into a stream of light, seeping into Mash's forehead.
"Eh? The water orb… it's gone?"
"This is a protection, Mash. A protection from the Water Fairy. May you grow up healthy from now on and truly see the world outside Chaldea in the future."
In the original storyline, Mash had journeyed through various Singularities and Lostbelts, experiencing countless extraordinary legends and adventures. But the real outside world, the current Human History—she had never seen it.
That's why, this time, Naoki was determined to take her out.
"Protection?"
Mash touched her forehead, her large eyes filled with great confusion.
The things this Big Brother who suddenly appeared said and did were things she didn't understand, things Doctor Roman had never told her about. But Mash didn't dislike these new things, nor did she dislike the Big Brother and Big Sister in front of her.
[When someone helps you or gives you a gift, you should say thank you. That's very important etiquette. Remember that, Mash.]
That's what Roman had once told her. So, she gave a small bow to Naoki and Gray.
"Thank you, Big Brother Naoki and Big Sister Gray."