The emergency stairs were equipped with Ether Lights, or AL, which were still functioning; their dim glow allowed the group to descend without any trouble.
"It seems the minimum necessary maintenance is still being carried out," Jin remarked.
Without it, the air likely would have become unbreathable long ago. Laojun had investigated the ventilation system in advance, which was why Jin and the others were able to step into the depths of the ruins without concern.
"Watch your step, everyone," Jin called out to the others following behind him.
"Kufu, I'll be fine. I've been spending a lot more time outdoors lately," Saki replied.
Ever since she had started spending more time with Goose, Saki—who had once been a dedicated homebody—seemed to be conducting her research in the field more and more frequently.
After descending about ten meters, they reached a landing with a door.
"Well, what’s the plan? Should we open this door and investigate this level, or head down further?" Reconaus asked, turning back to gather everyone's opinion.
"Let’s see. I think it would be best to investigate them in order," Jin suggested.
"Hmm, yeah. I think proceeding one floor at a time is the right way to go," Hanna added.
"I agree with Jin," Saki said.
Everyone agreed to open the door. Since there was no complex lock, it swung open immediately.
"Hmm. I don’t know how many years have passed, but the fact that nothing has corroded is impressive," Reconaus noted.
Moreover, no dust had accumulated. This was a clear sign that the air conditioning was functioning normally. The lights had deteriorated and grown dim, but the facility still stood as a testament to superior technology.
"The ventilation system is near the surface, and it’s pumping fresh air down into the underground," Jin explained, elaborating on the structure. He added that this was why he hadn't detected any movement of mana on this floor yet.
Beyond the door was a small, spacious lobby about the size of ten tatami mats, with another door visible further inside.
"Is this some kind of buffer zone?" Goose wondered aloud. He stared at the characters written next to the inner door. "Ah, it looks like this level is a residential district."
He had become quite proficient at deciphering the script of the Progenitors. As their research progressed, they had discovered that there were different variations of the script and language used by the Progenitors. Whether this was due to ethnic differences, regional dialects, or some other purpose remained unknown. In the case of these ruins, the difference in the language was roughly equivalent to the distinction between literary and colloquial Japanese.
"A residential district, huh..."
Reconaus judged that while they might make cultural discoveries here, they were unlikely to find major technical breakthroughs. He made a suggestion. "My brother and I will investigate this level. Jin-dono, I’d like to ask you and Sion's group to handle the floor below."
Since there seemed to be no immediate danger, Jin had no objections. However, just in case, he had Smith 1 accompany them. Thus, the brothers Reconaus and Tonelius, along with Smith 1, began exploring the residential district.
Jin, Hanna, Saki, Goose, Sion, Marikka, Reiko, and Nurse Alpha headed further downstairs.
After descending another fifteen meters, they reached a dead end at a single door. Goose squinted at the characters written upon it.
"Let’s see... 'Im... por... tant... ma... chin... er... y... with... in... au... thor... ized... per... son... nel... on... ly.'"
Important machinery within. Authorized personnel only. Entry by others is strictly prohibited.
"This sounds like the technological level," Jin said.
"If that's the case, the security might still be active. Onii-chan, we have to be careful," Hanna warned.
"Yeah, you're right." Even without Hanna’s warning, Jin was already on his guard. "Reiko, what do you see beyond the door?"
"Yes, Father... I detect no active magi-devices or magi-machines. There also appears to be no flow of mana."
"Good."
The total absence of mana flow meant that there weren't even any magi-machines in a standby state. As long as they didn't move unless they were woken up, the danger was minimal. Of course, with Reiko present and the barrier projectors built into their bracelets, it would take an incredible level of technology to truly threaten them.
Still, Jin remained cautious as he examined the door. "Hmm... it looks like security will activate unless a password is provided."
"A password?" Sion asked.
"Yeah....Reiko, I'll leave this to you."
"Yes, please leave it to me."
Reiko placed her right palm against the door and established an Information Link using mana. "It is indeed requesting a password."
At the same time, Reiko opened a parallel Information Link with Laojun. By doing this, she could utilize its vast information-processing capabilities.
Laojun, please analyze the password.
«Understood, Reiko-san. Leave it to me.»
Laojun began the analysis. The alphabet used on Planet Ars consisted of twenty-six characters, plus ten digits. While there were many special symbols, it began with the 105 most common ones. It tested combinations at sub-microsecond speeds, monitoring the system's reaction. When it hit a correct character, the response was slightly different.
The first character was 'v'. The next was 'a'...
In about one second, Laojun finished the analysis.
"I have it. The password is 'valcen27z'."
The moment Reiko reported it, the door’s lock disengaged. Reiko opened it gently, revealing a small, dimly lit room.
"Another buffer zone, it seems," Goose said, immediately stepping in to investigate.
"Oh, is this a map?" Hanna had found a diagram on the wall that looked like a floor plan.
"Oh, nice find, Hanna-chan!" Saki walked over and peered at the map over Hanna’s shoulder. Saki stood at 158 centimeters, just a bit taller than Hanna’s 155.
"Hmm... Oh, this looks interesting!" Hanna pointed to an area labeled 'Repository'. She, too, was becoming adept at reading the Progenitor language.
"I see. That seems like the best place to check first," Jin agreed.
Sion and Marikka had no objections, so they decided to follow the map toward the Repository. The corridor remained dim as they walked.
"Let me check something." Jin placed his hand on a section of the wall and used Trace System, followed by Inspection. Both were types of magi-craft used to investigate the flow of mana and structural integrity. "...I see. It's here."
Jin pushed a specific part of the wall, and the section recessed in a rectangular shape. He hooked his fingers into the gap and pulled; a maintenance door swung open. It was made of the same material as the wall to keep it hidden.
"Ohh!"
"As expected of Jin-sama-shu!" Marikka exclaimed.
Ignoring the praise from his companions, Jin checked the components inside that resembled a distribution board. "Ah, here it is."
Jin made a slight adjustment, and the lights illuminating the corridor suddenly brightened.
"It was in nightlight mode. I've switched it to normal mode now," Jin explained. "It was likely set that way to save mana and prevent the equipment from wearing out."
With the increased visibility, their progress became much easier.
"Following the map... we go straight down the hallway, turn right at the end..." Hanna walked at a brisk pace, narrating their path. "Here!"
The door to the room labeled 'Repository' was already wide open.
"Wait...?"
When they cautiously peered inside, they found the interior in a state of absolute chaos. The shelves that had presumably held documents and materials were almost entirely empty, their contents strewn about or missing entirely.
"What is this...?" Hanna whispered.
"No way..." Saki added.
Hanna, Saki—everyone in the group—stood frozen at the entrance, overcome by a wave of crushing disappointment.