Someone knocks on the door, it must be Satsukawa.
Good timing. I didn't quite like where the conversation with my butler was going. It is really unsettling when someone appears to know more things about your personal life than he is supposed to. I know that well, I frequently use that as a weapon, and I don't like it when it is used against me.
Rokudou opens the door for Satsukawa, and he comes inside with a joyful gait.
Satsukawa: "Good morning, everyone!"
Rokudou: "Good morning, Satsukawa-san."
He seems to be in high spirits. He is carrying a huge cardboard box that appears to be quite heavy.
Erika: "Is that a gift for me? How thoughtful."
Satsukawa: "Yes, something like that."
He puts the box on the table, next to the empty teacup. The loud sound it made confirms my first impression on its weight. I already have an idea of what is inside, but just to be sure...
Erika: "What did you bring?"
Satsukawa: "The paperwork you requested yesterday. These are the crimes that were reported around this area for the past two years. And that's not even all of them, of course, just the ones you're interested in."
Rokudou: "It looks like there's quite a lot of documents in there, hu hu hu."
Satsukawa: "Have fun browsing through them."
Erika: "I can't help but detecting a note of sarcasm. Is this the reason you're so happy, today?"
Satsukawa: "Not quite. Well, that too..."
Erika: "Then I guess there's something more important to discuss than a pile of papers. What news do you bring?"
Satsukawa: "Straight to business, uh?"
Erika: "If you've found new evidences regarding the case, I want you to tell me about them without delay. I don't want to waste my time speculating about theories that don't match with known facts."
Satsukawa: "Well, you're really going to love what I'm going to tell you. That was one of your theories, and now we've found something that supports it."
One of my theories? Which one?
Erika: "Where? When? How did you find new elements to solve the case without me? Explain."
Satsukawa takes an object from his pocket, and triumphantly hangs it in front of my eyes. It's a transparent plastic case, with a silvery disc inside. There are no labels of sort.
Erika: "A compact disc?"
Satsukawa: "Close, it's a DVD. This is yet again something that you requested."
Erika: "Ah, finally! I had almost forgotten about it. You sure took your time!"
Satsukawa: "There's a reason for that, and it took me a while to understand it... Actually, I'm not completely certain I do yet, but the geeks at the headquarter surely tried their best to explain it; they wouldn't stop talking..."
Erika: "Rokudou, can you bring my laptop here? It's over there, on the sofa."
Rokudou: "Hu hu hu. Certainly, Milady."
Erika: "Meanwhile, Satsukawa-san, you can try and tell me what you've learned from those 'geeks'."
Satsukawa: "Okay... Basically it's about how hard disks work when storing data. Apparently they divide information in many little clusters..."
Erika: "That's something everyone with a basic knowledge of computer science knows."
Satsukawa: "Oh... well... Anyway information is split randomly among those clusters..."
Erika: "I know."
Satsukawa: "And do you also know that when you delete a file, it doesn't actually get removed from the hard disk?"
Erika: "Is there anyone that doesn't? I mean, apart you."
Satsukawa: "Geez... sorry for being born in the sixties..."
Erika: "That's no excuse. To make it short, what they told you is that some files were deleted from the hard disk of Gotsuji's PC, but they still managed to retrieve them by examining the clusters into which their information was stored."
Satsukawa: "Yes, something like that... albeit I still don't quite understand why they're still there, if they were deleted."
Erika: "That's because when you delete a file, what actually gets deleted is the data necessary to retrieve it."
Satsukawa: "Ah, I know! That's what the trash can is for!"
Erika: "No... Nevermind, you're a lost cause."
Meanwhile Rokudou already finished preparing the laptop. Nowadays starting up the OS takes only a few seconds. I only wish Satsukawa's brain could be as fast.
Erika: "What exactly is inside that DVD?"
Satsukawa: "All the files that they managed to retrieve. Gotsuji's PC is an old model, so its hard disk isn't very voluminous. A single DVD was more than enough."
Erika: "Give me that."
I say so, while extending my hand, without hiding my annoyance.
Satsukawa: "I'm... not done explaining what's the important bit that we've found..."
Erika: "I'm trying to speed things up, it'll take hours at your pace. Just give me that DVD, you don't need it to explain."
Satsukawa reluctantly hands the disk over to me, while letting out a dejected sigh. Without delay, I put it inside the optical drive of my laptop.
Erika: "I assume that this important evidence comes from files that were deleted. You wouldn't try to explain all that computer stuff that you don't even understand for no reason, right?"
Satsukawa: "It's the web browser's cache."
Erika: "The browser's... cache, uh? I see... this is getting pretty interesting. Go on."
Satsukawa: "Basically the browser's cache is..."
Erika: "I know what a browser's cache is, Satsukawa-san. That's where temporary data downloaded from internet sites is stored. And I think I'm starting to get an idea of where this is leading us. By checking a browser's cache you can see which are the sites that the user visited in the past. There's certainly a lot you can learn from that."
Satsukawa: "Yes, that's what they told me, however it wasn't that simple, because apparently Gotsuji cleared the cache recently. In other words all those files were deleted."
Erika: "Considering we're talking about an old computer with a low capacity hard disk, that doesn't surprise me at all."
Satsukawa: "Well, at any rate they managed to retrieve part of that data from the clusters it was written into, but there's probably a lot missing."
Erika: "Because once files are deleted, the related clusters are considered empty by the computer and they can be overwritten at any time. When that happens the previously stored data is lost forever. It's pretty clear. What I don't get is why this is so important. We're talking about internet pages, right? Can't we simply look at the browser history and check those sites directly?"
Satsukawa: "Well, the problem is that the sites in question constantly change, so even if you go there now, you won't see the same thing that Gotsuji saw at that time. Then again, I guess that what really matters is that she browsed them, so you do have a point..."
Erika: "What kind of sites are we talking about?"
Satsukawa: "Why don't you check them directly? There, they conveniently placed the relevant retrieved data inside that directory."
After clicking on the icon that Satsukawa indicated, a list of html files appears on the screen.
Satsukawa: "Choose any."
I do as he suggests, and the web browser installed on my laptop automatically starts; its window maximized occupies the whole screen. Both Satsukawa and Rokudou, standing behind me, lean over to take a closer look. The page is obviously lacking some graphic elements, files that were lost and couldn't be retrieved; the textual content should be, however, complete. There are still several pictures that can be seen, pictures of people.
Erika: "What is this?"
Satsukawa: "It's a page from a dating site."
Erika: "A dating site... Now, this is getting really interesting."
Satsukawa: "Then you're going to love what I'm going to say next. This and the others aren't exactly the kind of dating sites where people look for long term relationships."
Erika: "Ha ha ha! Yes, I'm loving it, tell me more."
I quickly open the other files. Exactly as Satsukawa said, they come from many different dating sites.
Satsukawa: "There's a special section of the MPD that deals with sex crimes, we consulted them and they told us that many of those sites are well known to them."
Erika: "Considering the strict definition of 'prostitution' in the current law system, I doubt they can do anything about that."
Satsukawa: "That's only true for those that are 18 or older. A few years ago the government approved a law that forbids any kind of compensated obscene acts for those who are under that age. This is why the police is monitoring those sites to make sure they aren't used by children."
Erika: "Then what we're talking about is enjo kosai after all."
Satsukawa: "Originally it was a phenomenon strictly related to telephone clubs, but at this point those have become obsolete. Nowadays internet dating sites are used in their place. Technically you need to be at least 18 years old to even be allowed to access them, but all it takes to lie is a single click."
Erika: "And Gotsuji suddenly became interested in those sites. This is really great news, awesome! Did you tell her father already?"
Erika: "Nevermind. More importantly, have you established when she accessed those pages?"
Satsukawa: "Yes, that was between the last December and January. The current theory is that during that time she was evaluating the idea of getting extra money through compensated dating. She probably visited many of those dating sites to get an idea of how they worked. In the browser history there's evidence that she actively researched the subject. However there's still the possibility that she was just curious, we don't know if she actually ended up selling herself."
Erika: "And yet, that would explain how she was able to make all those expensive purchases. In addition the times match. As far as we know she never bought anything that she couldn't normally afford before the present year."
Satsukawa: "Well... that's certainly true... But if she created an account, evidence of that should appear on her computer."
Erika: "That page might be one of those that couldn't be retrieved. It might be worth to try checking the actual sites."
Satsukawa: "That's what the geeks were asked to do, but they said there isn't a big chance they'll find anything."
Erika: "Why so?"
Satsukawa: "When it's young girls making those announcements, they usually give false information. For example they all write they're 18 years old, which is the minimum allowed age. They rarely upload pictures, and when they do, they make it so they can't be easily recognized. Then there's the fact that those sites constantly change, so Gotsuji's account could've been deleted already by now."
Erika: "I see. At any rate I think this is a very important evidence."
Satsukawa: "Even if you say so, I can't help but thinking that this just complicates our work. This opens the possibility that Gotsuji was killed by one of her clients, and then we'll never find him."
Erika: "Don't be so negative, Satsukawa-san. Everything suggests that the culprit is related to the Mitsugi institute."
Satsukawa: "Well, I hope you're right."
Erika: "I'm always right."