The Doorframe's Trigger
The most universal image that comes to mind when one hears the word "door" is a rectangle—one with a handle, capable of being opened and closed, and sometimes even fitted with a lock. "Since people are the ones who defined what a door is, if something is recognized as a door within their common perception, then it naturally becomes a door."
"So... you're saying it's literally a door."
Becoming a thief who steals the door to the women's restroom felt oddly embarrassing, but when you're trapped and on the verge of dying, there's little you won't try. "Nngh..."
Creak, creak...! Even though the door looked old and its coating had peeled away, it was far sturdier than expected. No matter how much force I applied, it refused to simply snap off.
"Step aside, please."
Crash...! Crack...!
The Team Leader grabbed my shoulder and pulled me back. She gripped the door firmly with both hands and kicked the lower hinge with all her strength, shattering it in one blow. After shaking the door a few more times to loosen the remaining hinge, she checked that the panel itself hadn't broken and carried it vertically toward the entrance.
She hadn't even seemed to use any particular superhuman strength, which only made my own clumsy struggle with the door moments earlier feel all the more pathetic. My face burned with embarrassment.
"Shall we give it a try? Hold on to my shoulder tightly."
Paying no mind to my hesitation, the Team Leader advanced toward the restroom entrance she had already confirmed was blocked, holding the door like a shield. With no choice but to follow, I gripped her shoulder. I braced myself for the inevitable impact against empty air and squeezed my eyes shut—only to realize my steps carried me much farther than expected before gradually slowing down.
"...?"
When I opened my eyes, thinking we hadn't collided after all, the scene before me was no longer the inside of the restroom. Yet we hadn't been transported to some entirely different location either. The entrance to the women's restroom we had just escaped from and the cracked tile floor that had tormented my back were both clearly visible right behind us.
"This is... a hallway."
"Remember this well, Ung-ssi."
"Pardon?"
"Once you figure out the activation conditions of an ability, you can respond appropriately. Depending on the situation, it's even possible to neutralize it without using any special powers of your own. Abilities are never omnipotent. Most come with penalties, and they operate on a fairly simple principle: they produce results only when specific conditions are met."
My own ability, for instance, requires that the other person be close enough for me to directly perceive them before I can attempt a connection. Distance, direct sensory recognition, and that somewhat abstract final condition—that I must seek understanding of their heart. If even one of these isn't satisfied, my ability gives no response.
Perhaps spatial abilities work the same way. They too require conditions, and if any remain unmet, the effect is nullified. Maybe their conditions are even stricter.
"If the person who helped shoot down the plane you were on is the same ability user currently occupying this space... then fundamentally, her ability's result is the creation of a window that connects two separate spaces."
"But... this time we weren't moved anywhere else."
"Exactly. And from that, we can easily infer that one of the conditions is that the target or location must be something she has directly seen."
Still holding the door in front of her, the Team Leader continued walking. Just as our escape from the restroom hadn't been a coincidence, when she aligned the door with its frame once more, we passed through without any obstruction and entered the stairwell.
Now able to head upward safely, we could return to the temporary base where the others had gathered. With a slightly calmer pace, as if she finally had some breathing room, the Team Leader continued my lesson while climbing the stairs.
"However, using an ability of that scale consumes a great deal of stamina and mental energy. The farther the distance, and the more windows she keeps open, the greater the cost."
"...Otherwise it would be troublesome."
I recalled Yerin once saying that her own ability grew stronger the closer the target was, the more their gaze focused on her, and the more her gaze focused on them. It would be dangerous if an ability capable of tilting the very balance of existence had no conditions or restrictions at all.
"Heh, yes. I don't know how many windows she's opened inside this building, but maintaining the effect for days without rest is nearly impossible. That's where the concepts of occupation and triggers come into play."
"...You don't leave the lights on at home all the time, do you? You usually turn them on when it gets dark."
"...?"
"But does that mean you turn them on every single time it gets dark? No. You only turn them on when you enter, turn them off when you're done, and switch everything off again when you go to sleep."
"What have you been muttering about since earlier...? So you're saying the master is here? I think I can smell something faint..."
Glare.
"Fine, fine... I'll be quiet, so stop glaring at me with those eyes."
Those jet-black eyes, like black pearls, reflected none of the surrounding light when examined closely—an unnatural shape. Though the girl wore a mischievous smile on her cute face, meeting those eyes instinctively made one's body stiffen.
On the rooftop of the building next to the abandoned structure sealed off by the field team, a girl with strikingly long black hair fluttering in the wind sat beside a sleek black cat. They had erased their presence and were chatting leisurely right next to the field team members who were on alert with sniper rifles set up.
"In short, just as you perceive your surroundings through your five senses, she expands her perception range by occupying space and sets triggers within it to reduce the burden of manifesting her ability."
"...Even if you explain it so kindly, I still don't understand what you're talking about..."
The cat grumbled and sprawled on its belly, but the girl continued gazing with her pitch-black eyes at the eerie sight of the silent, abandoned building.
She had set the trigger so that any living being passing through a "doorframe" would produce the same result as passing through one of her windows. The interesting part was that she had tied this to the human concept of a "doorframe"—something that shouldn't inherently relate to her ability at all. By removing every door attached to the frame, she had successfully redefined it as a passage.
"I don't know who she is, but she's quite skilled. If this is talent, it's impressive. If it's the result of learning, that's interesting too. But... it looks like Oppa has already gotten close to the answer himself."
Thus, any change applied to the doorframe would affect the connected ability as well. If the doorframe—originally meant for doors—were to close as intended, the meaning of the passage would be severed, and the window would shut.
"Ehehe..."
Feeling a surge of new inspiration, she wanted nothing more than to return and craft new toys. Yet she had come all this way using the promise she made with that foolish, jealous cat as an excuse. There was a reason.
...Sigh.
Nero swallowed a sigh while secretly glaring at the terrifying black-haired girl who had suddenly appeared, dredged up that embarrassing old promise, and dragged her out in the middle of the night.
"Just where is Master, and what is he doing...?"
She could see plenty of people who looked like staff from Master's workplace gathered suspiciously around the neighboring building. But Master's scent had cut off, and this unfathomable monster had brought her here only to tell her to wait quietly while she became completely absorbed in something else.
"..."
From what little she'd overheard, it seemed certain that Master was inside that rundown building. Should she sneak in and check...? The very idea of being brought all the way here and told to sit outside and watch quietly was contradictory to begin with.
If Master—who had already saved her life twice—was in danger, this clever cat couldn't just sit still and do nothing.
Nero lightly leapt onto the rooftop railing and, without looking back, skillfully landed on the rooftop of the abandoned building at just the right height for a jump. Only then did she feel guilty for breaking the girl's order. She timidly glanced over her shoulder—and saw something unexpected.
"...?"
The black-haired girl who had told her to stay put was now waving her hand as if to say "have a safe trip."