Métisse sat in the dimly lit study, the ARON book splayed open on the table. The ancient, leather-bound tome emanated an eerie presence. Only one page was filled with illustrations and texts that had perplexed them since they first discovered it. The Fall of Civilization. But it looked like nonsense at first.

She had decoded a bit of it during her free time, but today, they were determined to finish the puzzle and complete the story. It was still frustrating that all the other pages were blank.

"These types of puzzles typically involve solving visual and textual clues to piece together a larger story, sometimes referred to as "cryptograms" or "pictograms" when heavily focused on symbols and images. Just like this one."

The others gathered around her, each holding fragments of notes and sketches they had been working on. The ARON book contained mysterious contents hinting at some really interesting but dark stuff.

Métisse's voice was steady but full of anticipation when she announced, "Let's start with the stick people illustrations and drawings. They seem to be connected to the creatures and experiments described in this book."

The stick people drawings were strangely compelling, depicting scenes of chaos and transformation. At first glance, they seemed like mere doodles, but upon closer inspection, they revealed a horrifying story.

"They aren't just random," Métisse continued. "They depict the end of the world. Well, the end of a world."

Métisse pointed to a series of drawings showing figures transforming into grotesque animals. "All I know is that these are definitely ancient and forbidden experiments." She explained, "Performed by the scientists of the old world."

The girls leaned in closer, captivated.

"Look at this," Sanaa said, pointing to a drawing of a half-human, half-plant creature with tendrils sprouting from its body. "There's portrayals of forbidden alchemy. I found the name of it from the archives. That's all I got."

Asher shuddered. "Gross."

"But why are these experiments hidden in this book?" Jingwei asked in confusion. "And why do some of the recipes in the cookbook section seem so strange? I can't even fathom these ingredients."

Métisse sighed. "The book seems to be a record of knowledge that was probably too dangerous or corrupt to be kept in the open. Because all of these figures in the photo perish at the end of the story. Maybe many of their experiments ended in disaster, creating people with severe genetic abnormalities."

"If this is true, it's yet another reason we must repopulate the world with care and precision. We can't allow anything as abhorrent as that to happen again. After all, repeating the past is a hallmark of insanity," Asher declared.

Samaira sighed, bored, and slumped into her chair. "So...these aren't just fictional tales? Like Santa? And mutants? Or are they? That still tells us nothing of great importance. It's literally just a history lesson."

The room fell silent as the girls absorbed the gravity of their discoveries. The ARON book did not seem like a mere fictional story; like the other tamer ones they'd been told about. It was a chilling record of humanity's darkest ambitions and failures. Sanaa was undeterred, believing that every story was based on some sort of credibility.

"What about the...cookbook section?" Asher asked, breaking the silence. "It surprisingly seems the most odd and out of place, actually."

Métisse nodded. "That's something I'm still working on...these are foods and products we've never seen or eaten before."

As they brainstormed, Sanaa announced softly, "It's not just a code to be cracked, but a story to be understood, right? Each symbol, and each seemingly random ingredient can be pieces of a larger whole."

"Like a cake. Or pizza." Jingwei mused.

Adorable. Sanaa grinned. "Yes!"

"But, what I don't get is which civilization is this? Did this actually happen to our world...or people from a different one completely?" Samaira asked with uncertainty.

"Not sure..." Métisse muttered in the same tone. Through the doubts about the story's true origins, they felt a strong compulsion to go deeper. Even if they didn't find anything suspicious, this book was entertainment for them, transmitting knowledge with photos that they had never laid their eyes on before.

Jingwei had mentioned earlier that the book didn't give her a bad feeling or spiritual unrest, so at least the girls were slightly confident that it wasn't providing dark magic instructions or evil, poisonous recipes. They trusted and were now more confident in her than ever.

As the session drew to a close, they felt a mix of dread and curiosity. The ARON book was a Pandora's box of forbidden tales, and they had only just begun to scratch the surface. Although seemingly insignificant, the story was still enjoyable and thrilling for the girls to unravel and demystify, never having had the chance to read exciting books like this all their lives.

"We need to keep studying this," Métisse said, closing the book gently. "There's so much more to uncover. But we must be careful. The stuff on this page was hidden like that for a reason."

The girls were in agreement. They knew that their journey into the book's ancient mystery was far from over, and the path they walked was fraught with peril and intrigue.

...

Sanaa's footsteps echoed softly down the corridor as she made her way to the Medical Health Center. Her mind buzzed with anticipation, a mixture of nerves and determination propelling her forward. She needed answers, and she needed them now.

Entering the centre, Sanaa approached the reception desk with a feigned cough, hoping to catch the attention of someone. As she waited, her mind raced with thoughts of K8-LYN and the mysterious patterns she had noticed in the binary code.

Sanaa was relieved when the EchoChamber's AI health robot, Aegis, glided up to assist her instead. This was just what she needed, Sanaa didn't need to find Aegis, because it found her first.

"Bonjour, mademoiselle," Aegis greeted in a soft French accent, which surprised her for some reason. "How may I assist you today?"

Sanaa quickly feigned a pained expression. "I have a terrible migraine," she whimpered, pressing her fingers to her temples. "I think I need a check-up. Immediately."

She hoped her bad acting didn't catch onto the AI. "It's been persistent for days."

"Of course," Aegis replied sympathetically. "The front desk team is currently on their lunch break, so I am handling medical assistance for the next few hours. The other staff are busy with their shifts."

Sanaa managed a weak smile, impressed by the AI's reassuring presence. "Thank you, ah, Aegis right?"

"Indeed," Aegis responded politely. "Please follow me to the examination room."

As they walked, Aegis continued to speak, "I will begin by taking your vital signs and asking a few questions to better understand your symptoms. Do you experience migraines often?"

"Not usually," Sanaa replied, maintaining her act. "But this one feels different - worse."

Aegis led her into a sleek, modern examination room and gestured for her to sit down. "I see. Let's proceed with the check-up and do our best to alleviate your discomfort."

While Aegis continued to remind her about scheduling appointments and obtaining a teacher's note, Sanaa's attention drifted to the blinking lights and monitor screens around her. The rhythmic beeping and flickering of the displays had a strangely soothing effect, reminiscent of the comforting sounds in a hospital.

It was almost hypnotic, the constant beeping of the nearby computer embedding itself in her mind like a consistent melody, drowning out Aegis's words.

As the robot worked and gathered supplies, Sanaa surreptitiously jotted down the sequences of random numbers that were flashing across the screen, recalling something distant. She couldn't resist writing the numbers that had embedded themselves in her mind like a catchy tune. It was hypnotising.

Sanaa quickly stopped when Aegis returned from the other room with a sphygmomanometer.

"Though this was unplanned, I am truly honoured to be in the presence of a Circle Sister. I will assist you today to the best of my abilities. Hopefully, to your comfortability with my services."

"Ah, thank you..." Sanaa blushed, feeling more embarrassed than flattered by the recognition and respect solely because she was a 'Circle Sister.' She politely asked, "Sorry, but why wouldn't I be comfortable with you?"

"I am programmed to respect any human's decision not to be assisted or operated on by an AI robot."

Sanaa nodded, cleared her throat, and decided to ask Aegis some casual questions.

"So, my science professor, Dr. Leroy, mentioned you're the university's advanced medical aid?"

"I am indeed acquainted with Dr. Leroy. He is our esteemed head of his division. He frequently comes in for treatment. To clarify, I am the system Aegis for the entire EchoChamber."

Sanaa raised her eyebrows in genuine shock. "Why does he always need treatment?"

"Dr. Leroy seems to be quite accident-prone, Miss. He usually finds himself in unfortunate situations, from chemical spills to food poisoning. We also have to stitch him up weekly due to various wounds and cuts."

Sanaa let out a surprised laugh, the explanation fitting perfectly with his unusual and hectic behaviour.

"That sounds exactly like him, actually," she commented, amused.

Sanaa cleared her throat, glancing at Aegis with curiosity. "Do you know a K8-LYN AI...or any other specialised robots that are still active?"

Aegis answered, "My primary function is to protect the health of the community. The K8-LYN bot, however, was in charge of you five Sisters. She and I were the only ones of our kind. Since K8-LYN completed her mission, I have had no access to her database due to her immediate deactivation."

Sanaa's face fell, a hint of sadness clouding her features, but she clung to a sliver of hope. Aegis noticed and offered a more reassuring, less automated, tone. "Do not worry. We are content with our core operations. I, too, will be deactivated once I've served my purpose. Once we expand. K8-LYN must have served well for you to miss her so much."

As Aegis finished measuring her blood pressure, noting the levels were fine, she prepared to suggest an injection for further testing.

Sanaa quickly interrupted, "No, thank you. Ah, I just remembered, I have an important meeting with my advisor in a few minutes."

She really disliked needles. Her visit there was just about over.

Aegis nodded understandingly. "Of course, Miss. However, your health and comfort are my priority. Is there anything else I can assist you with before you go?"

Sanaa replied in a rush, "I'll come back after class for pain killers or something..." She stood up, searching for a polite exit. "Thank you for your help, Aegis. I appreciate it."

"Of course. Take care," Aegis replied warmly.

With a grateful nod, Sanaa left the medical centre, ambivalent but grateful for the interaction.

...

Later, back in the dorm room, Sanaa spread out her notes on the table, her friends gathering around with a mixture of curiosity and excitement. Métisse, with her musical expertise, recognized the patterns in the binary code, likening them to the notes of a melody.

Suddenly, it clicked. The distinct exclamation of "oh" that K8-LYN often used could be translated to the number zero. Sanaa's heart raced with excitement as she realised she might be onto something.

With Métisse's guidance, they began to decode K8-LYN's messages, uncovering warnings and clues hidden within the sequences of ones and zeroes. It was like piecing together a puzzle, each bit of information unlocking another piece of the mystery.

As they worked, Jingwei's absence of glowing became a concern. Despite their efforts to coax her into replicating the phenomenon, she could not summon the glow again. Nonetheless, they pressed on, determined to unravel the secrets hidden within the code.

Finally, they stumbled upon the realisation that "ARON" might not be a person's name after all, but rather a code word or anagram. They played a game of hangman, trying different combinations of letters to see what made sense. From the letters "ARON," they managed to come up with a few potential words: "ROAN," "NORA," and "ORAN." Each possibility sparked new questions and theories, fueling their determination to uncover the truth.

As all else had failed or confused them, Asher offered the Brute Force Approach learned in her class. She described, "we just have to systematically try substituting different letters into the word, A R O N, until we find a combination that makes sense..."

"And in the given context," Sanaa mumbled exasperatedly as she lay her head on the desk.

"While this method will be time-consuming, it can possibly eventually lead to cracking the code," Asher finished.

"Alright..." Samaira said slowly, "So...we start by looking at the letters in 'ARON', and try adding different ones to form a more cohesive word. Yes?"

Asher nodded proudly in confirmation, "Exactly, Sam."

They then tried to solve it alphabetically and began writing:

ARON + A = AARON

ARON + B = BARON

ARON + C = CARON

ARON + A + B = AB RON...?

....Metisse offered the latter, trying to both add and combine the first two letters instead.

Samaira groaned, "Good idea...but agh, this will take forever...Mei, you do that, while we continue alphabetically. Baby steps."

Jingwei then added onto Asher's method, suggesting the Frequency Analysis method.

"...we simply consider the frequency of letters in the English language." She explained further to clarify, "Since "A", "R", and "O" are already present in "ARON", let's focus on adding letters that commonly follow these letters. For example, "F" is a common letter that can follow 'A'. "

After what felt like an exhaustive process, they all sat back, feeling a sense of weariness but also satisfaction. They collectively reviewed the list of potential words, carefully selecting the ones that seemed most promising.

ARON + F = FARON

ARON + H = HARON

ARON + M + R = MARRON?

...

Sanaa's eyelids fluttered open to find her Sisters gathered around her, their expressions tinged with worry. They were accustomed to her moments of absentmindedness, but this time felt different. It lingered longer, prompting them to believe she had drifted off to sleep while still upright.

"Hey, you okay?" Samaira's voice cut through the fog of confusion, her concern evident. "Did you just doze off or something...? Where did you go just now?"

"What do you mean?" Sanaa blinked in dazed confusion as her gaze swept over her Sisters "Wait. What day is it?" she murmured quickly, the words feeling heavy on her tongue.

Jingwei's response came slow and cautious. "It's still Thursday, San. We've been here the whole time."

"We were trying to figure out the code and I think you...fell asleep?" Métisse said while eyeing Sanaa warily, as though she were a dangerous animal. "You've been...drifting again."

Sanaa remembered that look from long ago. In their youth. That's how everyone looked at her after her...'terrible incident'.

Sanaa expressed her confusion, stating that she had thought they all went to bed after their session of deciphering the code. She believed she had just woken up the next day. But to her surprise, it was still the same day, and they were still gathered in the dorm room. She noticed a piece of paint peeling off the wall, and it irked her more than it should have. This had been happening frequently lately, but Sanaa foolishly dismissed it as mere stress. 

She had become so consumed by her research that she would doze off, only to wake up in another room. Or she'd look away for a moment and find that the conversation and setting had shifted completely. It was becoming increasingly uncanny and distorted.

A flicker of disorientation crossed Sanaa's features. "Thursday? But I thought..." Her sentence trailed off as she got lost in the disarray of her thoughts.

Métisse's voice, gentle yet insistent, broke through the fog. "You haven't been sleeping well lately, Sanaa. Maybe it's time to consider talking to Lenora about medication. We've all noticed how much you've been struggling with the nightmares again. I think they're getting worse."

Sanaa's attempt at reassurance fell short, evident in the lingering worry etched across her Sisters' faces. She offered a sheepish apology, acknowledging the spontaneous unease she'd caused them. 

Mustering a weak smile, she said quietly, "Sorry. I guess I am just a little tired. But yeah, I'll definitely talk to Lenora about it."

"You're still trembling, San," Samaira noted.

Cause it's so damn cold in here. "Must've just zoned out there for a moment... or longer."

Asher inquired carefully, "Has the...sleepwalking returned or...?"

"No, no, no..." Sanaa hastily interjected, recalling the unsettling episodes she used to have as a child.

She instinctively shuddered at the thought of them returning again. The last time she had sleepwalking problems, she'd almost done something... horrible. Without even realising it.

With a smile that didn't quite reach her eyes, Sanaa answered, "I suppose I just drifted off into a daydream..."