The material Mio worked from was the perpetrators' carcasses, gathered up by the police in the course of their cleanup.
Ads that had been reported and removed, frozen accounts, bands of IPs that had been switched out one after another. When she rearranged six months' worth of footprints, half of them had already withered.
"A domain's lifespan is a few hours. The IPs are disposable too. All of it built from the start on the assumption it'd be thrown away," Mio said, looking over the list she had extracted.
"They grow it back much faster than we can cut down one bundle. Taking them out one by one is a losing line. It's the same as slugging it out with the Hydra, that monster from the myth whose heads multiply as fast as you cut them off."
Cut off one head, and two grow back. Bouncing them as fast as they spring up is a tactic, not a strategy. If you want to stop it, the only way is to sever the body.
Done with chasing branches. Earlier that day, after seeing the police off, Mio had already decided as much.
Mio switched screens and began joining the dead dots with lines.
"The faces and IPs on the surface can be changed as often as they like. But—the way they're connected can't be. The same network, the same payment routes, the same bank accounts. Rebuilding those from scratch costs them too, so even they reuse the roots."
"Using that reuse is pivoting. From one withered branch, you dig up a root that's still alive."
Mio's fingers raced. The dots on the screen were turning into a mesh before their eyes.
"The nets so far looked at ads one at a time and guessed whether each was a scam. This one looks at the 'way the dots are connected,' all of it, and identifies the whole area. It's not a person finding them by hand. You throw a mountain of dots and their contents into the machine and let the network itself find 'the shape of a suspicious cluster.'"
"...This one's wrong," Mio said, removing a cluster that had swelled up partway through from the map.
Mikoshiba took note of the way she did it.
"You're removing it? A cluster that finally surfaced?"
"Unrelated companies that just happen to use the same hosting server. People who just live in the same apartment building aren't necessarily family, right? So I don't trust a single kind of connection. Only when payments, bank accounts, and more overlap, several strands of them, do I treat it as the body of the same creature."
Mikoshiba laughed low. "So you nearly framed someone."
The net, its training finished, brought out spots here and there in the mesh where the suspicion ran thick.
"Community detection and centrality. It looks scattered, but this is one organization. And this single point, where the lines gather so abnormally—that's the admin account redistributing faces and words. The command center for distribution."
"In other words, you find the cluster and name the one in the middle," Mikoshiba said.
"Right. But the command center that hands out the words and the crux that collects the money are separate."
Mio circled just the network of accounts in a different color.
"Connect the 'frozen accounts' and the 'money trail' the police had, and the root comes into focus. Disposable accounts that just lent their names, that money simply passes through—money mules. Countless of them, bundled together, being sucked into a single point. This account, where the most routes converge, is the aggregation account that siphons up the money. The crux of the money."
A root that bundled countless disposable branches. And deep within that root, a heart that siphoned up the money.
But at the very tip of the bundle of lines gathering toward the center, at the one point where something should have been, they broke off abruptly.
"...It breaks off here. Only the one point that leads further in has no record. It's not that there isn't one. They erased it. Only the most crucial relay left no footprints."
Mio gave the same net a different job. Not to identify faces, but to infer, from the habits of how things connected, the lines not yet drawn.
"If you look at how the surrounding dots are connected, you can read the lines that should extend next. If this many strands are gathering at one point—even if it's not in the records, there's always something at the center. You can erase a point, but not the lines heading toward it. The bundle of remaining lines traces the shape of the vanished point in reverse."
At Mio's fingertip, a faint outline bled into a blank point that existed nowhere in the data.
"...I see it," Mio murmured, glaring at the shadow of a formless hub that was in no one's records.
The map was done. But Mio wasn't pleased.
"I'll say this: we don't know yet if it's real. All the machine can say is 'there's something at this position.' Confirming it—is the police's job," Mio said, driving the point home flatly. She wouldn't let a prophecy turn into a conclusion.
"This is a picture of tonight only. By tomorrow morning, it'll already be out of date. But even if the branches change, the way you haul in the root doesn't. With the same method, I can redraw it as many times as I need."
Mio leaned back in her chair and rolled her stiff neck once. As she did, the company's own logs, always left open, caught the corner of her eye.
"This time, we could grasp the shape of the root because we had the police's data. But this net can haul in roots the same way when moved to different data. ...Meaning, even from just the records we bounce every night on Makoto."
Mikoshiba didn't interject. The profile that had just unraveled the police's carcasses was already peering into the next garden. He simply watched the light starting to glow in that one spot, unable to catch up.