Tokiwadai High School at night is definitely not bright. Due to the observation needs of the school observatory, in order to avoid light pollution, Tokiwa usually does not turn on any light source at night. Therefore,In the brightly lit school city,Tokiwadai at night seems strangely dark and quiet.。

Tokiwadai's soft school shoes barely make any sound when stepping on the stone-like non-slip floor. In this eeriely quiet environment, Shirai Kuroko even felt her heart beat faster.

Why come here? What do you really want to know?

She couldn't answer any of these questions. She wasn't even sure if she would run into anyone on this trip, but it was just another pure instinct that told her that she had to be here. The location doesn't even need to be told to anyone at all, even if it's just a matter of course, it's only that place.

Tokiwadai gymnasium.

Wait a minute, what will you see?

Shirai has always considered herself fearless and brave, but just thinking about it has a premonition that makes her extremely uneasy, and she can't help but sweat in her palms.

Although she was looking forward to her questions being answered, as she got closer to the gymnasium, the feeling of wanting to escape grew stronger in her heart. It wasn't clear to her, but it just made her feel a chill.

At the entrance of the gymnasium, there was a man standing.

Shirai couldn't help but be stunned. She thought of all kinds of possibilities, but there was no such person in either way.

"You ......"

Shirai wanted to speak, but the other party leaned over without saying a word, and gestured for her to follow. There is no commonplace teasing, very one-pointed.

Her very unusual reaction took Shirai away.

When she opened the door of the gymnasium and walked into the gymnasium, a chilling yin aura hit her. Shirai couldn't help but shiver before realizing that it was supposed to be the cold wind of the air conditioner.

There are only a few sets of lights on in the gymnasium, which looks a little dim, and there is no small figure in Xingchuan, and there is even a faint optical illusion in it.

When she spotted Shirai, she turned her head and nodded, turning her gaze to the bee-eating caustic prayer beside Shirai.

(These two men...... ）

Shirai frowned. She had no recollection of any connection between the two men.

"Don't get me wrong, I'm just a translator this time." Bee Eater whispered, "This is their home field, but you know Hoshikawa-san's situation, and she doesn't want you to misunderstand the meaning because of her expression barrier." ”

"They?"

Shirai was stunned. It was then that she noticed that it wasn't just the three of them Tokiwadai students in the gymnasium. On the vaulting side, there is also an upperclasswoman in a white lab coat fiddling with a glass cube of about 50 by 50 centimeters.

This schoolgirl wears rustic double braids, and although she looks quite delicate, she is not too conspicuous. But underneath the unbuttoned white coat, the black uniform of Foggy Hill Girls' School stood out here.

Shirai wondered why a student from Kirigaoka appeared in Tokiwadai, but the student spoke first.

"I think the 177 branch has done a good job, and you are the closest to the truth so far. I think next month, when I apply for funding, I will consider leaning towards the 177 branch. ”

This sounded a little inexplicable, but it reminded Shirai of the way she spoke in a way that didn't sound pleasant to the ears of the high-level members of the Discipline Inspection Committee when she attended the meeting just a few days ago.

That's right, this person is probably also a high-ranking member of the Discipline Inspection Commission. Although the content of the speech seemed a bit bureaucratic, the tone sounded quite helpless. In addition to this, there is an inexplicable "taste" like ......

That's right, it's like the detached feeling of an ascetic and enlightened monk.

Shirai can't quite describe the feeling, but it's undoubtedly out of place with the high school-age schoolgirls in front of him.

I just listened to the schoolgirl continue.

"Truth be told, I don't have a boring messianic complex, but I don't think it's right to leave the decision to someone else. In my opinion, that's just passing the buck. So Hoshikawa-san, your actions make me very embarrassed. ”

She looked up at Hoshikawa.

"Don't you think that a qualified leader should let the frontline staff have their own judgment?"

The person who answered was not Hoshikawa, but a bee-eater. But this passage itself is undoubtedly the words of Hoshikawa himself.

"What happened?"

Shirai asked.

Now, she realizes that something serious must have happened.

"Wait a minute, Shirai. We'll have to start from the beginning......"

"To put it simply, it's a virus."

The words of the schoolgirl in the foggy hill were just a start, and they were immediately interrupted by the bee-eater.

"Virus?"

"Wait a minute, Hoshikawa. Why are the juniors of this year so impolite? The schoolgirl in the foggy hill looked stunned, "Well, the truth is that as she said, there is a virus lurking in the school city, and it may break out and spread at any time." ”

"Shouldn't the epidemic prevention agencies take action? Could it be ......" Shirai's brow furrowed even tighter.

"You see, I just said don't get people wrong. Anyway, don't pay attention to those two guys, this level is not a virus, at most it is just some pre-programmed program. Although a virus can be considered a program, the so-called virus is not a simple and harmless thing. The schoolgirl in the foggy hill grabbed the back of her head with a helpless look. Or, to put it more bluntly, it doesn't have what it takes to succeed as a virus. The so-called virus is more than that. From a human point of view, it must at least be harmful to humans in the long term, and may have some ability to deliberately manipulate human behavior. ”

"What are you talking about? Controlling people's behavior? The virus deliberately manipulates people's behavior? ”

Shirai was confused.

"Hey, were you surprised? So come over and take a look at this. ”

The schoolgirl in the white lab coat reached for a flashlight from her pocket and shone the light into the glass box.

Shirai stepped forward and found only a few branches in the box, with a few snails crawling on it. But when she looked closely, a stomach-cramping feeling of nausea rushed up her throat.

The antennae of the snails in the glass box are abnormally enlarged, and through their translucent bodies, it is clear that something strange is wriggling inside the antennae and inside the body. It is this snail-like, yes snail's antennae that appear colorful and eerie.

"This is the famous double-disc fluke. Snails are only their intermediate hosts, they live in the snail's body, at first just eggs, and then hatch into white spores that are settled in the snail's liver. As the snails ingest nutrients, they absorb the nutrients ingested by the snails directly from the snails and grow into granules. But in my opinion, this is only the first stage, and the second stage is where the real attraction lies. Do you see that wriggling thing? That thing is the hatching sac. These parasites move inside the snail and eventually form a complete hatching sac in the tentacle part of the snail. And the wriggling of the larvae in the hatching sac is the cute situation you see. ”

"I think you should see a psychiatrist."

Shirai's cheeks twitched, and she couldn't accept the adjective "cute."

"I have my own psychiatrist license, so you can come to me if you need it." The white-coated schoolgirl shrugged disappreciatively, "Of course, what you just saw is not the point of my point here. The point is that in this second stage, the behavior of the snail as a host. ”

"I just feel disgusting, and it's pathetic."

"Well, having said that, you can't be emotional as a scholar." The white-coated schoolgirl chuckled, "I'm sure you should know that snails tend to be dark and damp. However, in the second stage of parasitism by the double disc fluke, the habits of these parasitic snails will undergo a 180° shift. They are phototaxis and will be keen to climb high places, as you can see now. ”

Shirai turned his head directly. As a girl, she has a physical aversion to this kind of thing.

"The point is, have you ever thought about the purpose of this change in the snail's habits?"

"What else can this kind of thing do?"

"Of course! Nature is amazing. As I said, snails are only intermediate hosts for Doubles and the ultimate host of Doubles is birds. Then the question arises, we all know that birds are usually active during the day, while snails are active at night, and the active period of the two is completely staggered, so how does the double disc fluke enter the body of birds through snails? ”

Shirai's face turned blue for a while.

"Phototaxis ......"

"Correct. As I said earlier, parasitic snails develop phototaxis, and the active phase shifts to daylight. That is, Diplopodium manipulates the behavior of the host. By the way, the creep of the hatching sac you just saw only happens when there is light. In other words, the double disc fluke can not only manipulate the host, but may also be able to simultaneously experience the host's perception of the outside world. The purpose of this wriggling is also obvious, and these two hypertrophied antennae appear to birds to resemble their predatory caterpillars. Phototaxis, combined with a tendency to crawl to higher heights, naturally increases the likelihood that snails will be preyed upon by birds. In fact, snails infested with Diplodium are probably more than three times as active as usual. ”

“……”

The physical disgust made Shirai sick to her stomach for a while, and she really didn't want to continue the topic, but the schoolgirl in the white coat preferred to continue talking as if she were happy.

"This parasitic mode of manipulating host behavior is actually very common in nature. For example, in addition to the double disc fluke, there is also this one. ”

The girl in the white coat raised her right hand, and at some point, she grabbed a struggling praying mantis in her right hand. She smiled at Shirai, then slammed the mantis to the ground and stomped it flat.

"Watch out."

She moved her flashlight to the mantis's corpse and motioned for Shirai to come up and watch.

From the body of the praying mantis, which had been trampled into meat sauce, a black thread writhed out and swung in circles on the floor.

"This is the nematode, another parasite that we are more familiar with. Its ultimate hosts are large animals, including us humans. And the intermediate host, that is, insects such as praying mantises. Like the double disc fluke, I am more concerned about how it behaves when it parasitizes on an intermediate host. Adult nematodes end up living in water and also need to lay eggs in the water where they hatch their larvae. Once the larvae are eaten by insects such as praying mantises, they form parasitic relationships in the body. Of course, that's not the point. The important point is that praying mantis is a terrestrial insect, while nematodes cannot lay eggs on land. Therefore, just like the double-disc fluke, the nematode also has a special set of skills for manipulating the host. Insects infested with nematodes develop unusually strong hydrotaxis, and these linear creatures manipulate the insects' behavior, forcing them to drown in water so that the adults can complete a new cycle of life in the water after they break out. ”

"What the hell are you trying to say?"

Shirai asked, holding back the growing panic in his body.

In fact, she more or less guessed some. But in any case, she is psychologically reluctant to make such conclusions.

"I mean, how exactly do you Tokiwadai educate your students?" The schoolgirl was stunned. "A change in habits, an increase in activity, and an increase in aggression...... Isn't that enough to remind you of something? You don't realize that the commotion you experienced before was not an unprovoked mass panic, right? ”