The searing white light blinded Accelerator, but he didn't loosen his hold on the book. He could hear Index's frantic voice far away, but he had no idea what she was saying. He could feel something inside him start burning. Gritting his teeth, he ignored the pain and attempted to will the light away. He suddenly heard the voice of a young girl.
"That won't work unless I'm the one doing it. Oh wait, I recognize you. Yahiko said you'd come looking for me. Well, looks like I can shut off the security measures." The white light died down as quickly as it had appeared. Realizing he wasn't holding on to the grimoire anymore, Accelerator looked around wildly to find himself in a library.
"Where am I, who are you and what do you want with me?!"
"You're inside a library, of course. Actually, this is another dimension, to be exact. Nice to meet you, Yahiko's kid. I'm the Moonlight Codex." The said grimoire appeared in front of him, the pages open to the middle. Abruptly, silver light surrounded the book, causing it to warp its form. When it finished, a short young girl stood in front of him, around Last Order's age. She had long silver hair, pale, almost translucent skin, and silver crescent pupils in ocean blue irises. She was wearing a whitish blue silky dress that floated around her, decorated with silver and gold accents on the edges. Her feet were bare.
Accelerator stared at the young girl in shock. "You're the Moonlight Codex?"
"Yahiko put a spell on me so I'm sentient and not just some dusty old grimoire like the others that are in the head of Index Librorum Prohibitorum. As an effect of that spell, I can also take on a human form. Again, I'll reiterate that I'm the Moonlight Codex."
"The human form of a grimoire seems quite young. Also, what's with the eyes?"
"Oh, I like this form. Much better than some old woman or something. Besides, I am called the Moonlight Codex because I was written under moonlight, hence my eyes. It's just a representation. By the way, you are Yahiko's kid, right?"
"I'm not a kid, and I barely know my father. However, the answer to that question is yes."
"You are a kid. I'm older than you, in fact. Well, I will run one test to confirm the truth."
"Hey, you said you turned off the security measures or whatever since you recognized me."
"Something about you just reminds me of Yahiko, but I like making sure. Now, give me your hand."
Extending his right hand, Accelerator started in surprise when the girl swiftly grabbed it. For a person who looked like a young girl, her grip was strong. To his surprise, she produced a knife and slashed it across his palm, drawing a large amount of blood to the surface, dripping in a steady stream onto the tiled ground.
"What the hell was tha—"
"Silentium."
The strange, harsh language Accelerator somewhat knew to be Latin made him close his mouth, despite the stinging pain from his hand.
As he watched, the girl closed her eyes, holding her hand out to catch some of the blood. "Cognoso: Accelerator, filius de Yahiko. Dubium."
Identify: Accelerator, son of Yahiko. Accepted. Wait, how did I figure that out?
A silver light burst into existence, surrounding the two. The young girl clasped her hands around Accelerator's bloody one, chanting. Somehow, Accelerator knew the words she was saying.
By the power in the Moonlight Codex, this grimoire will forever be embedded in your mind. By blood, we are bonded. I will be your helper. Awaken the secret power within this grimoire.
The silver light grew stronger, yet Accelerator wasn't blinded. He suddenly found himself on the rooftop again, Nagato and Index staring in awe. The light disappeared, leaving him and the young girl.
And finally, he blacked out.
***
"Oi, Accelerator, wake up!"
"What should we do, Nagato-san?"
"Leave him be. He will wake up around… now."
As if on cue, Accelerator opened his eyes to find Nagato and Index hovering over him. The girl stood nearby, a calm look on her face.
"About time you woke up."
"How long was I out?"
"Only a few minutes, but you were gone long enough for Index and I to panic. She was saying your presence had disappeared from her mind, and your body had disappeared as well. Not to mention the fact she can't remember anything from the Moonlight Codex anymore."
"That, I can explain." The girl walked up calmly, and helped Accelerator up.
Accelerator winced as the girl grabbed his cut hand. "The cut's still there, isn't it?"
"Yes. Don't worry, it's already healed. Right now, it's just a scar."
"Okay, I think Index and I agree on one thing right now. Explain. "
"Don't get all worked up, Nagato. You already know I'm the human form of the Moonlight Codex, due to an effect of Yahiko's spell. In reality, Index didn't just memorize me; she absorbed me. When Accelerator was exposed to the contents of the grimoire, the knowledge was transferred to him from Index-san, thereby allowing him to remember everything written inside me. However, Index will not be able to remember anything she saw in the codex."
"What's with the scar?"
"A binding spell, sealed by blood. Accelerator is free to use any spells I have, and I am his servant. Those were the orders from Yahiko himself."
Nagato's eyes widened. "Nii-san wanted all this to happen?"
"Yes."
"Well, am I supposed to feel any differ—whoa, what the hell is this?" Accelerator held up his right arm. A thin silver chain was wrapped around it, a silver-bound book dangling from the chain.
"The Moonlight Codex," Index gasped in surprise.
"That is essentially me. I'm just the alive and sentient part of it. That's just the original book. You can will it to appear and disappear whenever you want. Of course, all the content inside the book is already in your mind. However, if you need reference or help, just open the book."
"I see."
"Well, you're truly unique. I thought the Moonlight Codex was sealed away." Nagato watched Accelerator with something like awe in his eyes.
"In Index's mind. Also, please call me Kaguya."
"Okay then, Kaguya. Well, are you technically human or what?"
"Hm, I don't actually know. Well, I guess I can be classified as a human-like spirit. Yahiko never specified anything special for me when I was born. Well, I don't sleep, and I don't eat. Yeah, definitely not human. Also, don't let the Imagine Breaker near me, or else the magic in the Moonlight Codex will be destroyed."
"Okay, got it. But for now, are you going to be traipsing around in your human form?"
"Yeah. It's easier to communicate that way."
"Well, due to this unexpected turn of events, training's canceled. I was only planning for Index to show you the Moonlight Codex anyways, Accelerator."
"Doesn't mean you won't be hard on me tomorrow. One day of training and I already beat up a magician."
"You've progressed really quickly. I don't know what to do next. Well, I guess Kaguya can train you with the spells in the Moonlight Codex. I'll train Haruka when she wakes up."
"We should head back."
"Still hungry, Librorum Prohibitorum? You ate three times as much as us."
"If you tried the things Touma makes, of course you'd want to eat more foods that weren't made by him."
"Ha, I think the level 0 would take offense to that."
"Well, the earlier I get acquainted with the rest of the group, the better."
"Tch, wait until the brat sees you. She'll probably think you can be a new playmate, Kaguya."
"Don't call people brats. Still, who is she?"
"A clone. Her name's Last Order."
"Oh wait, that name sounds familiar."
"How would you know?"
"We are bonded. If I concentrate, I can probably read your mind and know everything you know."
"How about you do that, so there's less of a hassle?"
"Okay. Nagato, Index, please go on ahead. This will only take a few minutes."
Glancing at Kaguya suspiciously, Nagato turned and left, Index trailing after him. Arin turned to Accelerator.
"I'm going to need your hand again."
"If you're cutting me with that knife again, no way in hell."
"That was a one-time thing. Just stay still. The more I know, the fewer questions I have to ask, and the less annoyed you'll get. That is what you'd act like, am I right?"
"You look like a little kid, but you know a lot."
"Stop focusing on the appearance already. I'm at least a decade older than you. I just like this form. Now, shush."
Kaguya took his hand again, chanting. Wispy halos of light extended from Accelerator's head towards Kaguya. Within minutes, the spell finished.
"Done. Oh, now I know what you guys are talking about. Well, let's hurry down before Nagato-san and Index-san spoil all the surprises."
"Fine. Also, how can you penetrate my reflection?"
"Easy. There will always be a type of magic you cannot reflect, and that is the magic of grimoires."
"I see."
"Well then, lead the way."