I start the next morning with the sound of a sigh from Mirai, holding her head as if she is worried. The serious atmosphere is slowly taking control of the living room. I take out a cigarette from my shirt, burn its end with a lighter, and give her.

-          Hey, maybe you have smoked a cigarette once when you are still alive. This modified cigarette has chemicals that help to cool down electronic systems when burned, so for robots, it may feel like a relief feeling.

-          Thanks.

  Mirai is reading the collected data from the tablet, which are just a bunch of graphs and numbers dancing and constantly changing. On the left corner of the tablet screen, there is the world map, densely marked with crosses, from green, to yellow and red.

-          As you can see, this graph here shows the distribution of the Intruders' force on Earth. There are about a million of them, with one Commander. If the Commander has an overall rating of a hundred per cent, and a normal Physical-class Intruder has an overall rating of zero per cent, the average rating of a million Intruders will be about thirty per cent. As we defeat them, their force will face a decline in number, but their overall rating will increase also. And we need to take into account if there will be reinforcements. - Mirai tells me, as she points at the jumping numbers and fluctuating graph lines.

  A million Intruders... Average rating of thirty per cent... The overall rating graph looks like a negative exponential distribution, which means about half of their force, five hundred thousand, will be Physical class. Not that much of a pain, but the other half of the graph is really troublesome.

-          By the way, since you are here already, let us continue our lesson from yesterday. Rankings.

  There we go again. I sit down on the sofa, next to her. I feel the heat from the electronic components running at full power from Mirai. This is what people would call seriousness. A visible seriousness.

-          The rankings of Intruders just work the same as our human army. A million Intruders, one Commander. First, the Commander class has the rank of General, because this one has every stat at the top level, and the ability to lead. The million-numbered army is split into five grand divisions, each taking control of one continent. Each division is led by a Colonel. Then, in grand divisions, there are divisions to take control of individual big countries and territories, each led by a Captain. These division leaders all have high stats and are subject to promotion to Commander class, so they are dangerous also. There are other ranks amongst the Intruders, but their stats are negligible. Once you defeat the leader of a division or their whole division except the leader, you clear that division. - Mirai opens another tab from the tablet and accesses the Intruders' encyclopedia.

  Not an easy task, but it is doable. This ranking is easier to understand than the Class, maybe because she cuts off the insignificant part. But something is missing...

-          Ah, yes! This is the Intruder simulator to help you visualise the overall rating. - Mirai presses a small button on the screen, and it directs the signal to the holographic screen in the living room.

  The hologram shows disgusting-look, Physical-class Intruders with a zero per cent rating and a fake human target. The Intruders mindlessly charge towards the target, holding a weapon in their hands, maybe hand, and shoot in every direction. Only one or two hit the target. So this one has every one of its stats at zero.

-          That is what you get for a zero overall rating. Every stat is near zero, and as a result, they just follow the orders of the higher-ups. Their weakness is also the upper region. In fact, it is true for most Intruders.

-          OK, understood. Next one. 

  Then, the overall rating is increased to twenty-five per cent. The hologram now shows an Intruder with a more advanced weapon and armour. It can target humans and finish the fake target off faster. It seems to have higher strength, agility and intelligence, but not so significant.

-          This is a higher rating Intruder. These types will appear at higher-level facilities more frequently. Dealing with them is a bit troublesome, but we can pull it off with good tactics.

-          Can they control vehicles yet? - I ask.

-          Ground, maybe. Aerial, not yet. Their intelligence stats is still limited in some sense.

  The current overall rating is fifty per cent. The Intruder starts to look more human-like. They can now partially mimic human appearance using their own light-diffraction technology, but they cannot mimic human behaviour, except simple speech, so I would have no problem spotting them from normal humans by interaction. They are more swift and accurate, as well as wielding more equipment and cutting-edge weapons. At this rating, they can start leading lower rank Intruders. If I am to be one-versus-one with a fifty per cent rated Intruder, I still can gain an advantage, hopefully.

-          Now, we officially move to the middle-level rating types. The Intruders at this level can be recruited into Technician or Scientist classes. I mean, as far as human technology goes, and with what information we have, we can still beat them. But in large numbers, they pose a great threat. 

  Mirai takes out a stick, similar to the types teachers at school would use. She points at the upper chest area. It lights up to highlight the region she is pointing to.

-          Their region of weakness is also reduced. Their core is located here, in the middle of the upper chest, but a bit to the left, like our heart. Of course, aiming at their head still deal good damage, though.

-          OK, I still understand so far. Next.

  The hologram changes to an Intruder with a seventy-five per cent rating. It now looks and behaves more like a human, maybe to infiltrate normal human society. They do not directly join battles but are seen to lead squads and divisions of Intruders of lower rank. They can deploy aerial attacks and satellites to specific areas. So very high intelligence and slightly improved strength and agility.

-          From here, we are just hopeless against their attack. Pulling our trump cards may luckily kill, like, one or two of them, but that is all. 

  Mirai does not look like she wants to talk about the level that we cannot even deal with. She just silently raises the rating for me to see myself.

  The last part is utterly horrific. The hologram shows a Commander-class Intruder. That thing now is completely indistinguishable from a typical human. In a tick, it changes to its true form, very buffed-looking with all the muscle-like limbs. Its normal punch breaks a concrete wall, and its gamut of weapons can detonate a stupidly huge radius. Not only that, it leads a bunch of Intruders with a really close overall rating, about more than ninety per cent, with somewhat the same ability. According to the hologram, high-rating Intruders can use the Invisibility technology, and if you do not have high-quality thermal vision goggles or something similar, you spray and pray, before it approaches you and sends you to Heaven. Mirai does not make a single comment and lets me inspect it myself.

-          OK, that is it for the ranking part. Now, we have this more important part. - Mirai returns to the tab where the numbers are jumping again. She enlarges the world map densely marked with crosses that I have seen half an hour ago.

-          Here, the crosses mark out the bases and towers of the Intruders. From green to red, they signal the danger level of the bases. The higher the danger level, the harder it is for us to attack, but it also means the higher the significance of the bases for their army and the harder it is for them to repair if they are damaged. What we attacked during our first mission is just a green-level facility, a reconnaissance tower, so probably by now, they have repaired them already. - Mirai continues her lecture.

-          Unless we shut down every green-level facility at once. The damage would be somewhat similar to shutting down a red-level facility. - I contribute my idea.

-          That is a good idea, but there are, like, thousands of such towers out there. Where do you get the manpower from?

-          The towers in close proximity should be linked to each other to transmit information. If you can create a virus able to spread between towers, there will be quite long-lasting damage. Then, for the next part, while the Intruders are trying to fix the problem, we attack a yellow or red-level facility.

-          That is a brilliant idea... Why did I never think of that?

  Indeed, we do not need to physically destroy every single tower. We destroy the system linking them together, and the outcome is similar even with less effort.

-          Or I have this better idea. We attack this facility here, the main information transmission mini-island, a yellow facility, and we can technically disable every single reconnaissance tower that this island takes control of. - I continue suggesting, seeking approval.

-          Also a good idea. But before that...

-          Yes?

-          You have the brains, but you lack the physical strength and agility, thanks to your couch potato lifestyle of a freelancer who sits in front of your working table twelve hours a day. For the next few months, we will only play around with green-level facilities for you to build up your pitiful muscles. Tomorrow, we will attack this storage, somewhere here. And I will teach you how to ride a plane to save yourself in case of an emergency also. - The elated voice suddenly falls down to a teacher's kind of voice, scolding her students.

  What a pain, what a pain...

_________________________________________________

  Somewhere around the cluster of Ogasawara Islands, flocks of planes, like the night crows in the dark sky, circle around the ruins of the fierce battle, leaving a damaged tower, and countless pieces of metal from planes scattering around. Lieutenant Colonel, head of the K1 Squad of CEA, New York City branch, stands in front of the screen, recording the ruins in real time, a burning cigarette in his mouth. A loud shout from the communication device, and plane after plane, in neatly arranged lines, land on the cliff. Troops in fully-equipped weapons, one by one, swiftly proceed to the ruined tower. From the command of Lieutenant Colonel, they knock on the door and run inside.

  Soon, every soldier fills in the tower, mapping out everything. One has reached the control room. With a military camera in his pocket and a flashlight to brighten the room, he takes pictures of the place and sends them to the headquarter. Another has also reached. An information technology expert. He has a set of hacking devices, and with some plugging and clicking sound, everything is extracted. He checks again if everything is neatly compressed into a single folder, then signals the rest to leave.

  The planes of some unknown enemies have arrived, only tens of miles away. The troops enter the planes and evacuate. Under the command of Lieutenant Colonel, anti-plane lasers from deployed satellites pin down the whole cluster of islands. Having escaped, the troops look at the island they just left. The unknown planes are roasted in a few thousands degree Celsius of the laser, adding to the graveyard of pieces of junk metals. Mission complete. Lieutenant Colonel has finished his cigarette. A bin is right under his table, and a flick from his experienced fingers sends the remnant of the cigarette to the bin. He has been doing so for twenty years of his services. A perfect flick.