"Where's business mode Si-yeon gone?" wonders Hyun-jae, sitting on a cushion next to Juheon.

(Who wraps an arm around her.)

"He'll be here once we've officially started."

Chun-hee is the last one to sit down, between Woo-young and Si-yeon. "Let's start, then."

"Very well. Now we focus on control security: how to make sure Kang Jaeha can't affect us, or that he's caught if he does. We've already got a few ideas, plus all of the reactive location security-increasing measures are also control security-increasing measures." He adds them to his fake blackboard: body cams (↑ control, = location, reactive) plus their footage being reviewed in real time (↑↑ control, ↓ location, proactive, with a side note that it's uncomfortable), civilian onlookers (↑ control, ↓ location, neutral) using instagram (↑↑ control, ↓↓ location, neutral), media (↑↑ control, ↓↓ location, proactive), media being told to not broadcast stuff live (↓ control, ↑↑ location, proactive), guild-controlled cameras onsite (↑↑ control, ↓ location, proactive), going into dungeons (↑↑ control, = location, proactive + reactive) unless Kang Jaeha manages to get into the dungeon anyway  (↓↓↓ control, ↓↓↓ location).

"What else do we have?"

"Woo-young, you don't need to know where someone is to teleport them, right?"

"Right, but the backlash cost gets really high; if I know literally nothing about where someone currently is and they turn out to be on the other side of the globe that might kill me on the spot. Add it to the list anyway, though, it's good to have as an option, you're right."

"What if you know their general location via GPS?"

"...like, giving them a tracker or something? That basically solves the increased cost issue."

"Hmm, a tracker by itself doesn't increase location security—if anything it reduces it, since the GPS information being available anywhere can be risky, but only a little bit—and it does increase control security." Reactive, though.

"There was the AI facial recognition idea, too."

"Right! There was that." Added.

"Would the onsite guild cameras be able to make use of AI, too?"

"Probably but we're still trying to avoid sharing the information that Kang Jaeha is a suspect, right?"

"Why are we? If he's a suspect in the actual shooting, isn't that... definitionally the kind of thing we might want to share with others?"

"I'm not saying I necessarily disagree, but there are a few things we need to consider before we do something like that."

(It's like he's a different person, when he's doing this.)

"First, there's always the problem of image. Since he's a public figure, if we spread this around he can sue us if we don't have hard proof due to the damage to his image.

"Then there's the problem that if he knows we're onto him he can work even harder to cover his tracks, or he can become more dangerous; I can dodge bullets and Juheon can tank them but the three of you aren't immune and we want to avoid that risk if we can. 

"And there's also the part where knowledge of Kang Jaeha's powers is secret, which even beyond the NDA makes it harder for us to prove wrongdoing. It's a very convenient excuse, to say that his power means that he needs to be placed in solitary confinement and communicate only via video, isn't it? People would definitely be suspicious."

"Tae-gun's word is worth a lot, though; he's famous, hardworking, has personally saved thousands of people and closed more dungeons than any other esper in the country..."

"Kang Jaeha is also famous, if somewhat less so, so it's not that straightforward, and again we don't actually have hard proof yet."

"Would it be possible for the cameras to do the AI thing without us having to inform someone that they should be looking for Kang Jaeha specifically?"

"This is honestly the sort of thing I'd want to ask Tae-gun about," Woo-young says after a beat of silence.

"We'll put a pin on it and he'll be able to opine in the morning."

"Woo-young, do you know how come Kang Jaeha's power isn't detectable by other espers?" The constraint of "no other espers can check anything directly" is quite stifling.

"Yeah. His power isn't really creating anything fake, exactly? When he makes you see a visual illusion, your actual visual nerves are actually being physically affected the same way they would if actual light had hit them. A better way to think of them might be imagining that he's causing a personalised hologram to appear, one that really is out there, so the fakeness isn't really in people's minds, so to speak."

"...that's such bullshit."

"But wait, wouldn't that mean that there are things that should be detectable?"

"Such as?"

"If he messes with people's memories, the gap should be visible, no? In that there'd be a stretch of time that has nothing which should have something."

"People forget things all the time, memories don't go into long term storage all that often. Do you remember the exact sentences I used just now to describe Kang Jaeha's powers? I don't."

"...still, there could be something there."

"We'll put a pin on that, too."

"A psychic esper who was watching multiple people at the same time could maybe notice that what one person was perceiving wasn't the same thing someone else next to them was?" Hyun-jae suggests. "For a more proactive idea of how psychic espers can help, even if they can't prevent the effect in the first place."

That goes on the list, too.

"Hye-jin said that the bigger worry she has is with her being used against her own values, which happens if he fakes a dungeon break or the feeling of of her being inside a dungeon. How do we avoid that?"

"Maybe... I could watch the two of them go into dungeons through a camera, they send—some signal, and if I receive the signal that means that they perceive themselves to be inside a dungeon even though they're not so I teleport them somewhere safe?"

"You don't even need to watch anything, right? If you receive the signal at all that means that they think they're going into a dungeon but actually aren't."

"Hmm, yeah, but I should know where they are—I guess the GPS helps with that."

"It doesn't need to be just when they go in. They turn the signal on when they go in but it keeps sending pings to you? And then they turn off just before they walk out? You should never receive the signal at all because it should only be active while they're inside, so if you do that means that either they think they got in but didn't or they think they didn't get out but did."

"Does it need to be Woo-young specifically? Couldn't we set something up with their systems directly, give the comms blanket permission to teleport them and then there's an external system that should itself be checking automatically for this signal and will teleport them if it ever receives it. Artificial Woo-young."

"Wow, am I that easily replaceable?"

"You'll always be number one in our hearts, Woo-young," says Si-yeon, writing all of these ideas down.

"How do we deal with dungeons that destroy or prevent electronics from functioning, though?"

"This method won't work directly for those but we could set something up specially for them? Automatically teleport the two as soon as they step out of such dungeons without waiting for any signals at all. ...that one might actually need to be me, I think the system as it currently is has some very tight security measures preventing you from teleporting anyone you want."

"That... feels like it straightforwardly covers the case of faking being in a dungeon? Are we missing anything?"

"If their commscreens got sabotaged somehow..."

"If their commscreens ever stop at any point when they're not in a dungeon that in itself should send out an alarm somewhere," Si-yeon suggests.

"...yeah, I think that covers it."

"Dungeon breaks are way harder, though."

"...could we have cameras by Nightmare checking whether Kang Jaeha is or isn't in the dungeon? We're straightforwardly safe from his powers whenever he is."

Si-yeon facepalms and writes that down. "Thank you, Hyun-jae, that's brilliant and obvious and I have no idea how we missed it this long."

"So, no dungeon breaks unless Kang Jaeha is 100% accounted for?"

"Unless he's been declared accounted for while Hye-jin and Tae-gun are in their silos, he could fake any reports they receive while they're out so they should only trust reports they receive from here."

"Oh, and I forgot to say, Hye-jin has an earring that requests a teleport so that she doesn't need to use the commscreen, Kang Jaeha probably can't fake the feeling of being teleported if he doesn't know that's what she's expecting will happen."

"...that's good but you made it sound like it's related to what we were just saying somehow?"

"Oh, I see. If they get a report that Kang Jaeha is in Nightmare and that there's a dungeon break they can teleport home without using the commscreen, which Kang Jaeha wouldn't know to fake, and then they can validate it."

"Yeah, that."

Written down!

"...I just had a thought I'm not smart enough to follow through but I think you are: aren't there cryptography things they could do? Like, get a request for typing a password somewhere, or calculating a number, and unless they do it right they get teleported away..."

"...oh, like a captcha but with encryption keys? I like it, that's a way they could verify that anything in particular is trustworthy. Actually, that's genius, Juheon, just make it so whenever they receive certain kinds of comms they have to validate a key they receive and if it gets successfully validated they're teleported somewhere secure, so they know that if they didn't get teleported the comms are being faked..."

"This is making me more concerned for Woo-young's safety, you know."

"...why? This would all be automated."

"You're the one who feeds the teleportation batteries. If you can't feed them, we only have until they run out before everything stops working..."

"Attach the systems to other teleporters too. But also there's a ton of my power saved up, more than enough to get everyone somewhere safe if I do get killed, at which point you all can reassess."

"You are really far too unbothered by the thought of dying."

"We can brainstorm ways to make me safe once we're done with this, how about? That'll be the only uncovered cell in my danger table then."

"...fine."

"Next thing I wanted to cover was, what else can Kang Jaeha do to fuck us over? Assume we're good on making sure our heroes never hurt innocents."

"...he could kidnap them."

"Not for very long, and I think us having proper GPS tracking for them plus all of the other automated surveillance tools we've got..."

"Turn the question around: if Kang Jaeha's goal is still to get Kim Hye-jin out of the picture and get Tae-gun back, what would he do?"

"...I'm not sure he can? Before Hye-jin maybe he could've, but at this point—hyung is in love with her, the only way he'd let her go would be if—she chose to leave."

"Well, he's clearly delusional anyway so let's entertain the hypothetical."

"Is there a way for him to make Tae-gun think Hye-jin left of her own volition? Presumably if she just vanished and wrote him a letter he wouldn't believe it... She'd need to still exist out there in the world, doing dungeons and everything, for him to believe it's real."

"Depending on how crazy he is he might consider 'kidnap Tae-gun, keep him in a box in a simulated reality for the rest of his life' to be a success."

"It's categorically impossible for him to do this for as long as I'm alive and even if I'm not there's no way the entirety of Korea and many other places besides wouldn't go on a manhunt to find Tae-gun. And Kang Jaeha may not be fully in touch with reality but I don't think he's so insane as to not consider that."

"What if he... doesn't get rid of Hye-jin?"

"...say more?"

"What if he concludes there's no way Tae-gun will forgive losing Hye-jin and so he wants to somehow get Tae-gun back without getting rid of her?"

"...the only way that could possibly happen would be if he got verifiably rid of all of his backlash, and I'm pretty sure Hye-jin would just veto it outright."

"Did he lose? Is it done, is it just a matter of convincing him that he's lost?"

"Assuming he doesn't go insane and try something self-destructive, maybe? I wish I understood the guy better than I do."

"Well, if so, we have a first idea for what to do to actually stop him rather than just protecting ourselves against him. Get him to understand that he's just not getting Tae-gun back, at all."

"He probably would do something crazy, wouldn't he?"

"He would."

Sigh. "Alright. Got our work cut out for us.

"Let's keep going."

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