When moving into Eientei, Eirin had established a set of priorities: it would need to meet Princess Kaguya's living standards, need to be functionally self-sufficient, and be outfitted with defenses capable of slowing down lunar pursuit and/or repelling terrestrial forces.
Most people would have been forced to choose between compromising the aesthetics of the building in the name of security or limiting their defenses to avoid defacing the property. Eirin, being a genius among geniuses, opted to take a third option.
While the building appeared to simply be a large far-eastern mansion, each and every part doubled as concealed armaments and traps. The floorboards were marked with concealed symbols, the walls were subspace pockets containing weaponry centuries beyond modern fare, and the entire compound could be rearranged and resized via spatial manipulation at a moment's notice.
On top of that, both magical and technological sensors had been placed throughout the compound, capable of tracking the movement and magical signature of anyone within ten miles across six dimensions. In the event unauthorized entities were detected, the system would activate the proportionate level of force in response.
So, it really wasn't much of a surprise when Okina exited the door to the sight of Yukari in the middle of a binding circle and staring down several dozen magitech turrets inscribed with high-quality purification runes.
She took a moment to look at the vast array of weapons meant to kill gods and youkai alike and back at the door, seemingly weighing her options. Unfortunately for Okina, it was at that moment she felt the door's connection to her realm snap.
She wanted to be shocked and panicked, really she did, but she had honestly expected this result the moment Yakumo told her where she wanted to go. The only question now was if Yagokoro would kill the pair or lock them up for experimentation.
Okina's money was on the former for Yakumo, but things could go either way for her. Hopefully, if it's the latter Satano and Mai can rescue her.
She was broken out of her thoughts by the pitter-patter of feet on the wooden floor. To her surprise, the one responsible was not Yagokoro, but a Rabbit Youkai barely taller than Okina's knee. Her pink nightgown swayed with every step, matching the bounces of her carrot necklace.
"You know, I always heard that The Youkai of Boundaries was some badass big-shot. Real dangerous schemer-type," she said, raising an eyebrow, amused red eyes taking in the scene. "Gotta say, I'm not really seeing it right now."
Yukari opened her mouth, no doubt to make some comment to try and save face, but Okina beat her to it.
"You have no idea," she deadpanned. "I'm half-convinced she's just incredibly lucky and made up the stories herself." Earning her a glare from the aforementioned youkai and an amused snort from the rabbit.
"Believe me, I know luck," she said, gesturing offhandedly at Yukari. "That lady doesn't have anything special. Would explain why the two of you ended up like this."
"Is it so hard to believe I might consider this a worthwhile risk?" Yukari asked, her voice dripping with exasperation.
"Yes." "Pretty much," the two replied.
She huffed frustratedly. "This is what I get for trying to be upfront about things for once."
"I'm pretty sure breaking into someone's house through the back door is the opposite of upfront," the rabbit said, the corner of her mouth turning upwards into a smirk. "What's so important that you'd just charge into the doc's defenses anyway?"
"Oh, not much," Yukari replied. "Milk, sugar, the impending end of all life. That sort of thing."
The rabbit didn't so much as bat an eyelash. "I gotta admit, I haven't heard that one before," she said, leaning forward. "So, what? You wanna get the doc's help with that?"
Yukari shrugged. "Needs must. Regardless of my personal opinion of her, she is one of the most brilliant minds around."
"Flattery will get you nowhere Yakumo," A new voice called out. From around the corner came Eirin Yagokoro herself, silver braid swinging behind her, and dark grey eyes taking in the scene with clinical detachment.
"Took you long enough," the rabbit said, showing not the slightest speck of subservience to the new arrival. "Figured you'd jump on this sort of thing a lot faster."
"I was making sure there weren't other intruders," Eirin explained, gesturing at Yukari. "If there's one rodent, there are probably more out of sight."
Yukari smiled back. "It's a pleasure to see you too Yagokoro," she said with forced cheer. "And is it really such an impossible idea that I might be willing to drop the skullduggery in light of the present crisis? There seems to be a great deal of confusion over the matter."
The renegade Lunarian's expression may as well have been carved from marble. "And breaking into my home is supposed to instill confidence in your claims?" She asked mockingly.
"Yeah, that didn't make much sense to me either," the rabbit girl commented.
Eirin glanced over at the speaker. "Tewi, thank you for keeping an eye on them, but I can handle things from here. Could you go around and inform everyone that the intruders have been captured?" She asked the seemingly young girl.
Tewi seemed to consider the idea for a minute before shrugging. "Eh, sure. Don't want anyone getting trigger happy and blowing holes in the place," she said, turning around to leave and waltzing back down the corner. Though not before throwing a wave and a "see you later," at Yukari and Okina. Leaving them with their unwilling host.
"So," Eirin began, staring at the pair with a gaze usually reserved for cockroaches and virulent disease, "I believe this is the part where you explain why exactly you felt the need to do this."
"Well it's not like I could just send you a letter," Yukari responded, rolling her eyes. "And if I'd tried to knock on your door, I wouldn't have gotten so much as a word in before you turned on your toys and tried to drive me away."
"So you went and recruited the secret god over there in order to bypass the defenses and get my attention more directly then?" Eirin turned her head toward Okina. "And how might she have convinced you to join in on this endeavor? I wasn't under the impression you were the type to play along with her games."
"Normally, I wouldn't give her the time of day," the god responded. "You're correct about that. Unfortunately, she happened to bring some matters to my attention that I can't ignore."
"You're referring to the events surrounding Salem I suppose?" Eirin scoffed. "Whatever judgment her foolish actions bring upon humanity and its spawn is their own concern," she stated bluntly. "I have no reason to involve myself with whatever plan Yakumo concocted."
"Oh, I think you do," Yukari chimed in, drawing the other two's attention back on her. "It might not matter to you if humanity is destroyed alongside gods and youkai, but I imagine you and your princess getting wiped away with them would be much more of a concern."
The doctor shot her a disbelieving glance at the idea. "Do you really think that I'm going to be swayed by as transparent a tactic as that?" She asked Yukari, insulted that the youkai even considered the idea.
"It's actually quite valid," Yukari countered smugly. "The Brother's creations rise up in rebellion against their makers, led by the person who manipulated the younger Brother. How much disrespect do you believe the God of Darkness could tolerate before he lashes out? How much before the God of Light lets him?"
"That's your best argument?" Eirin asked skeptically. "That instead of just removing the failed entities, all life would be thrown out? That the God of Darkness would unleash power great enough to kill even Hourai immortals when targeting impure beings?" Her tone grew more and more dismissive with every sentence.
"Exactly," Yukari said, nodding her head sagely. "Who lights the fuse is irrelevant, once the younger Brother snaps, he'll throw out the entire board."
"And you know this how?" Eirin asked, crossing her arms over her chest. "Are you going to tell me that you can somehow do what even the combined might of the Lunarians could not and view the Brother's futures?"
In response, Yukari waved her right arm, opening up a gap in the air. Before Erin could fire the bow and arrow she had summoned, drawn, and aimed in the blink of an eye, the darkness within gave way to an image.
An army of humans, youkai, and gods led by Salem herself stood before the two Brothers. As they prepared to attack, the God of Light looked over to his sibling and gave a sorrowful nod.
Just as the army fired a wave of magic and weaponry at the Brothers, the God of Darkness created and crushed an orb of energy, unleashing a pillar of purple destruction before the army's attacks could even reach him.
The light scoured the globe, erasing every trace of its former inhabitants. Hidden youkai villages were unmade alongside divine shrines, defenses that had weathered millennia torn down as easily as ramshackle huts.
Eientei was no expectation, the building and its terrestrial inhabitants gone within moments. Eirin and Kaguya lasted a handful of instants longer, having left behind the very concept of death through the Hourai Elixir.
However, the elixir was ultimately a reverse-engineered form of the immortality bestowed by the Waters of Light, albeit an improved one, and could not match up to the Younger Brother's wrath. The light of destruction overwhelmed them, erasing every last fragment of their existence.
The renegade duo weren't the only Lunarians to suffer the God of Darkness' wrath. Aside from creating the deadly wave, the younger Brother's attack extended far into the heavens, piercing the moon itself.
Whether out of a desire to put an end to his sibling's first creations or simply because he wanted to make a spectacle out of the end, the attack had struck the Lunar Capital, destroying it along with the rest of the first race.
It was on that note that Yukari closed the gap, cutting off the images of the now-broken moon.
"Does that answer your question?" Yukari asked the still-shaken Eirin, her face devoid of any mirth or insincerity.
Okina stared at the space where the gap had been moments ago in shock. Yukari might have convinced her of the possibility, but watching everything be destroyed made the threat real in a way hearing about it had not.
Meanwhile, Eirin was still recovering from the sight. One of the benefits of spending decades, if not centuries, studying her foe's powers in order to counter them was that she was one of the few beings who could actually tell what Yukari was doing. Which boundaries she was manipulating at any given moment.
And that portal had been the boundaries between present and future, not truth and lies or reality and illusion. It was uncontrolled and unfiltered, but it was the future. Or at least a possible future. One that blotted out all the other outcomes through sheer weight of temporal mass.
The technique was known in theory, but it was considered worthless due to the fact that viewing all futures at once would not only overload most beings' minds but provide no knowledge beyond a chaotic mishmash of probabilities. That it produced such a clear and coherent set of events could only mean that said events were effectively temporal certainties.
In any other place, she could still write off the sight as a possible trick. But in Eientei? Trapped in a binding circle and with sensors scrutinizing every detail of her actions? The Brain of The Moon was forced to concede to herself that this may well be genuine.
Of course, that raised the question of what exactly the Youkai of Boundaries thought she could do about the cataclysm. Contesting the power of the Gods was outright impossible, the only beings who could have the slightest chance of doing so were either weakened or more concerned with their own realms.
Mind racing, Eirin ran through the possible courses of action, using her understanding of Yukari's personality and goals to narrow them down to the most likely one. Countless strategies were raised and discarded in the span of moments until at last, she found the winning formula.
Schooling her features back into a stern mask, she focused her attention back on Yukari, who was staring intensely at her.
The youkai was not in the best of shape, having expended massive amounts of her reserves to push past the binding circle and generate the gap. Despite her efforts to avoid showing weakness, Yukari's body was trembling minutely, beads of sweat running down her forehead.
Yet her gaze did not falter even once. The look in her eyes demanded Eirin's answer to the request that had been posed before giving in to exhaustion could even be considered.
"How long?" The doctor asked. Her voice suddenly soft and fragile compared to the condescension of moments ago.
"Three years before the earliest trigger," the Gap Youkai replied, exhaustion clear in her voice.
Eirin closed her eyes for a moment and let out a sigh before meeting her 'guests' eyes once more.
"Assuming your plan is what I think it is," Yukari nodded in response. "How exactly were you intending to anchor the barrier? Eirin asked, in the tone of one who knew the answers but wanted to see which one the other person chose.
"We'll need a mediating authority, someone to keep everyone involved from waging outright war amongst ourselves, so I was thinking about killing two birds with one stone and recruiting the Hakurei," Yukari replied, some of the tension leaving her body.
"You want to make a clan of youkai-hunters the lynchpin of a pocket reality containing large numbers of youkai?" Eirin asked skeptically. "Their skills and deity may be well-suited for such an endeavor, but their temperament is very much not."
"Perhaps," Yukari admitted. "But if forced to choose between hunting youkai and protecting humans, their priority will be the latter. It might not be something they would like, but the clan could adapt."
She took a breath and continued. "For this to work, we need to be able to maintain the balance of faith and fear between humans, gods, and youkai. While the situation prior to Salem has done a good job of conditioning all involved parties to uphold the status quo, I can't count on that lasting without humans capable of pushing back whenever it's needed"
"In other words," Eirin began. "None of your pawns would be able to play the role convincingly, whether because of a lack of ability or reputation, so you're forced to outsource."
"We can't afford to cut corners with this project," the youkai stated bluntly. "If I need to go through some extra effort to ensure quality performance, then so be it."
"Oh, so that was the other reason you came to me," Okina chimed in, the sound drawing the pair's attention to their somewhat-forgotten third member. At some point, she had leaned back against the wall, arms crossed over her chest.
"I can create whatever environment is needed for the refugees, but you need a way to ensure that it won't be destroyed when the time comes." The Secret God stated. "Me to establish the land, the Hakurei for the barriers and order, and Yagokoro and her princess to ensure our creation can make it to safety. Correct?"
"More or less," Yukari said, waving her hand in a 'so so' gesture.
"Regardless," Eirin stated, folding her arms and drawing attention back to her. "Whether or not I assist with this plan is up to the princess. I will give my opinion, but the final decision is hers."
Yukari let out an exasperated sigh. "The end of the world and you still defer judgment to her. I'm not sure whether such loyalty is praiseworthy or contemptible."
"Your opinions are as unnecessary as your continued presence," Eirin stated, throwing an annoyed glance at the Gap Youkai. "If you want an answer regarding my cooperation, return in a week's time. Until then, might I suggest you focus your energy on the many parts of your plan which you have yet to even begin?"
"As you wish," Yukari acquiesced, turning back towards the door they entered from.
"Are you coming?" She called to Okina over her shoulder as she strode towards the exit. Moments before she reached it, the Secret God felt the doors' connection to her domain re-establish itself.
Indeed, upon being opened by Yukari, the door revealed the Land of Back Doors rather than the back end of the compound. She stepped through the threshold, Okina following suit after a last glance at Eirin.
Of course, the moment the door closed behind them, the connection was once again sealed, a padlock even appearing over their end of the door to drive the point home. Prompting Yukari to roll her eyes at the renegade Lunarian's dramatics before turning to face Okina.
"Well, as much as it leaves a bad taste in my mouth, I'm going to take Yagokoro's advice and go speak to the Hakurei." She told her companion. "Can you get started on your end, or do you need anything first?"
The Secret God was almost offended by the insinuation. "As if I would need assistance for such a simple task," she declared, sneering at the very idea. "Go take care of your errands, I can handle my own matters well enough."
Sighing internally at her allies' need to make a spectacle, Yukari just nodded and exited the dimension through one of her gaps.
Okina paid little attention to her departure, her thoughts on how to best approach this new task as she headed towards her home. Hopefully, she would return before Satano and Mai got anxious and enacted the backup plan.