There was a visit on the schedule first thing in the afternoon, for three people.
When Mikoshiba said so, Mio didn't look up from her monitor. Sigma's reception area was visible through the glass. At one in the afternoon, two men and a woman in suits appeared. The man in front set down a single business card.
"We're from the prefectural police, Cybercrime Division."
If the business at hand carried the scent of data, she didn't want to miss it. Mio stood before anyone called her and took the chair at the end of the reception area.
"I'll get straight to the point," said the man with the card. "Investment scams using social media are surging. The losses in the past six months are double what they were the previous year. We're freezing accounts and getting accounts deleted, but we can't keep up. We get rid of them, and they spring right back up."
Spring up. It was the same word as the unease she herself had found in the company's own logs the night before.
The man paused, then shifted his gaze to Mikoshiba.
"To be frank, we don't often go around bowing our heads to the private sector. But we've heard your company's name a few times at the front lines of victim consultations. That they stop scams before they go out. That there's an operator who keeps from ever springing up, on the inside, the things we're always chasing after and crushing. If so, then someone with that method might be able to read the 'shape' of this forest. ...So we came, grasping at straws."
Mikoshiba's expression barely changed. But Mio knew. This man moved the corner of his mouth, ever so slightly, only when someone from outside praised the company. Just now, it had moved. Its reputation had been walking around out there, as much as the nights it had held the line had earned.
The female detective took over. Her voice was matter-of-fact.
"We're always cleaning up after a case that's already happened, so we can't grasp at all what shape the phenomenon takes as a whole, or what connects to what, and how. Even if we crush the individual accounts one by one, the next week the same scheme is up and running again, with accounts under numbers we don't know and domains we've never seen. All we have is an axe that fells the trees one at a time. We have no map of the forest."
The man lifted the bag beside his knee to show them.
"If it's a pile of carcasses you want, we have one right here. Reported scam ads, domains we've taken down, accounts we've frozen, IPs we've secured. The perpetrators' footprints. Could you analyze this data and draw us a map that traces the people behind it?"
After a short pause, Mikoshiba answered.
"We'll take it on. However, we only look at the data. We'll draw the map, but kicking down the doors and going in is for the police to do. We won't go to the scene."
"We appreciate it," the female detective said with a deep nod.
"One thing to confirm," Mio went on. "The victims' personal information?"
"We can't hand that over straight away. Once you've shown us the shape of the data and we've been able to decide 'what to ask for,' we issue a formal investigative inquiry. If the order is reversed, we can't put out the paperwork. We'd like to borrow your strength for that very first step."
Mio gave a small nod.
"The order is right. First, grasp the shape using only the perpetrators' footprints. Only once you can see where the crux is do you decide 'what to cross-reference and receive.' There's no reason to hand over a key first to a box whose contents you don't know. ...Information like individuals' ages can wait until the shape is visible."
The corners of the female detective's mouth relaxed, just slightly. Perhaps it had surprised her to have the paperwork procedure affirmed not as their own inconvenience, but on its logic.
After the three had left, Aya stopped her design work and came over to peek.
"So? Has the data come in already?"
"The perpetrators' part—the contents of that bag just now. No personal information in it. A pile of empty shells."
Mio went back to her own seat and opened the logs. Six months' worth of data the police had gathered up each time they cleaned up after a case. She ran down it one line at a time, top to bottom. The text of reported ads, the domains they redirected to, the IPs behind those, the account numbers that had sucked in the money. Lined up in order of date, it looked less like a record of incidents than a pile of shells left behind after molting.
Aya peered at the screen from behind and frowned. "...They're all different accounts. How can you even tell it's the same people?"
"The text is close. The way they punctuate, where they break lines, even their habits with emoji—uniform, like they were stamped out. People are good at hiding their fingerprints, but they can't easily shed their writing habits." Mio stopped scrolling and put two reports side by side.
"This domain was registered last week. Owner concealed. Gone in three days. This one next to it, the same. From birth, to use, to being discarded: seventy-two hours. Built from the start on the assumption it'd be thrown away."
"The same scheme turns up again and again with a different face. The ad wording and how the place they lure people to is built are almost identical. And yet the accounts, the domains, the IPs are all different. Yesterday's IP isn't in use anymore. They throw away the faces. They don't throw themselves away."
As she scrolled, the movement of Mio's fingers gradually slowed.
Next to the date the police had crushed one, another had risen up. The number rising up the next day was always greater than the number crushed. From the mark left where one had been pulled out, the next was already sprouting.
"...Even if you cut one, they rebuild faster."
Mikoshiba set a coffee on the edge of Mio's desk. "Can you keep up by hand?"
"No. This is a contest of addition and subtraction, and the loss was decided from the start. One side can mass-produce as cheaply as it likes, on the assumption it's all disposable. The other side crushes them one by one, by hand. The speed of increase and the speed of decrease differ by orders of magnitude."
Mio scrolled all the way down to the bottom of the screen in one go. "Even if you multiplied the crushing a hundredfold, far from catching up, the gap would only widen. It's not even cat and mouse. There are a hundred mice, and we have two hands."
"So what should we do?"
"—Stop slugging it out in a ring we can't win in."
Mikoshiba slid the coffee he had left on the edge of the desk to just within reach of Mio's fingers. He said nothing.
The feel of the sticky note she had stuck on the company's own logs last night flickered through her mind. That warning she'd sensed: you can't chase them one at a time. The Makoto of that night, and the pile of the police's that had just come out of the bag—the reason they kept springing up surely lay in the same place.
Mio looked across the screen with cold eyes. Her voice was hardening, low.
"Faces and domains can be painted over as often as you like. But the path the money takes, and the way they're connected—those can't be changed so easily. ...Erase the surface, and the way they're connected remains."
Aya and Mikoshiba exchanged looks.
Mio was no longer looking at the two of them. She was gazing even deeper than a single line in the logs. Not at each individual shell, but at the unseen creature shedding them, one after another.
"So—I'm done chasing branches."
Done with the arithmetic of chasing by hand.
Then what she needed next was a net that grabbed them not one at a time, but as a whole cluster, from the root.