Chapter 530 - Rat Breeding Survey Results
The next day, we left the medical research institute and decided to go to the monster testing ground where Eleanor-sama keeps rats and slugs. Recently, the Lich has been living there, but he's busy being fully occupied with the Dragonewts. He's scheduled to be away until summer. Matilda, who hates rats, parted with us at the research institute. The participants were the Henry Party, Harrison-san, Harris-sama, Beatrix, Mary, and me.
The monster testing ground is located near the medical research institute and the agricultural testing ground, but most of the facilities are underground. Like the fox breeding ground I saw once before, rats are kept in cages. They also handle earthworms and slugs. They seem to be considering tests above ground as well, and a new construction plan is reportedly underway. That said, since the Henry Party is practically building it, the costs are probably minimal.
The above-ground building, surrounded by a grove of trees in a corner of the forest, is a log cabin where staff and visitors can stay. The large rocks scattered behind the cabin are likely materials for stonework. There's also something like a water tank, perhaps for breeding earthworms.
When the bowl landed in front of the cabin, several staff members came out.
Here too, several disabled veterans are employed as staff. They were former soldiers of the Kingdom's Magic Corps and former heavy infantry. Their main job is feeding, and they apparently vary the amount of food based on the experimental plans created by Eleanor-sama and the Lich.
"Is everyone doing well?"
"Was everyone healthy? Please have some of this."
Will offered a barrel of wine, and Bonnie offered a barrel of dried meat.
After the greetings were over, we were shown inside the cabin. We were guided to a large room that served as a living room, dining room, and meeting room, and when we all sat on the benches, the staff brought out beer. Since there were magic soldiers, it was well-chilled.
When Eleanor-sama caught their eyes and all the staff went outside to stand guard, Eleanor-sama stood up.
It seems the survey results regarding the ecology of the rats Eleanor-sama is keeping have been summarized to some extent. She's going to present them.
However, they apparently need to observe a bit more, so the creation of the formal record will be a bit later. She manages it together with the monster-loving Lich, but the Lich is busy with the Dragonewts' fertility treatments. By now, he should be at the Silver Mine in the Northeastern Forest with Gnome to check the mana density of the era before Amphipteres were born. Consequently, the final report will be delayed. It will also be late to inform King Seldic, but the other party is in the middle of a war. He probably won't be in a hurry.
"According to the Lich, he can't say anything for certain until he's done several replication experiments, but he says what's currently known is about eighty percent correct."
I feel like eighty percent is enough, but the Lich wants to push it as far as possible. Being someone who has researched monsters for two thousand years, he has his obsessions. Incidentally, no matter how many times the experiment is repeated, it will never reach one hundred percent, at most around ninety-five percent. Considering the difference between experimental and natural environments and the existence of exceptions, it won't reach one hundred percent.
"Even with what's known at this point, quite interesting things have been discovered. According to the Lich, it might apply not just to rats, but to monsters as a whole, and by extension, to all living things residing on the White Island, including humans."
Originally, it was supposed to be a survey about the breeding cycle and generation gap of rats that never seem to go away. Before I knew it, it had become a grand story.
"Rats generally reach a mating season once a month, mate, and give birth. The number of offspring per birth is twelve. Since growth takes roughly half a month, they become adults the following month, reach a mating season like their parents, mate, and give birth. In other words, if there's an initial pair of two, there will be fourteen the next month, ninety-eight the month after that, and after one year, there will be—wait for it—27,682,574,402 rats."
It's already strange. If rats increased at that pace, the White Island would be buried in rats.
"Ahahaha! Oh, Eleanor-sama, that's way too many no matter how you look at it. There wouldn't be enough food. Ahahaha."
It was Mary. Shoot, she beat me to it. And her way of laughing was unlike her.
Bishop Phillips laughed along, Bonnie and Will laughed too, and finally, everyone laughed.
Eleanor-sama looked satisfied. Only Henry-sama had a sour face. No, Wilson-san was looking down and hiding his face, but he wasn't laughing.
"As expected of Mary. You understand well in many senses."
The 'many senses' part is a bit concerning.
Of course, there's no way rats would become twenty billion in a year.
"Actually, the cycle of the mating season and the number of births change depending on the quality and quantity of food."
"There you go again, that's too much of a joke. Ahahaha."
"Jeanne. This is actually true."
Mary cleared her throat with a 'co-hon.'
Huh? No one is laughing...
"S-sorry..."
"No, no."
That triumphant fist pump of hers is annoying.
It was true that the way rats increase changes depending on food. That makes sense in its own way. It's probably because they would die without food. However, according to Eleanor-sama's story, the rats themselves are controlling their numbers. They change the pace of having children according to the food situation, always securing a population appropriate for the environment.
"Ordinary rats don't control the population of the pack to this extent. Growth is influenced by the environment, including the death of children, and if the environment worsens, they migrate. In the case of monsters, it seems they can control the population of the pack through the presence or absence of mating seasons before it comes to that."
Foxes and boars have their numbers determined to some extent by the location. That's why if you hunt and reduce their numbers, they won't come out for a while. Instead, ordinary foxes and boars increase. After that, based on the thinking until now, foxes and boars that have accumulated mana in the forest come out. If the food available around human settlements is constant, the population also stabilizes at an appropriate number. If humans hunt desperately, they temporarily disappear. For now, it's consistent.
"From the things seen and heard until now, it was assumed that if there was a massive amount of food, they would increase tremendously, and then start cannibalizing each other once they ate all the food. That was an error."
If it's not cannibalism, then...
"It has been found that if food is extremely abundant, or if the quality is extremely good, large individuals grow. And that size was the same as when they grew in an environment with dense mana."
In that case, if we improve the food situation for the Dragonewts too...
"It's not that simple. Regarding the state of the fetus and the children that are born, they are no different from other individuals. In the case of rats, individuals that continue to grow even after becoming adults occur. Besides, in the case of rats, they are just stronger because their bodies are larger. In other words, the quality of their abilities doesn't change, but they become individuals with a large output... that is, quantity."
The physical difference between Amphipteres and Dragonewts diverges during the growth process, but their abilities are likely completely different. The fact that they don't have parental affection might mean there's an even bigger difference. The Dragonewts called it a throwback.
"The conclusion is that if the food situation for the rats in the sewers worsens significantly, we might be able to significantly reduce the population, just like the foxes and boars that appear near human settlements."
The view of Eleanor-sama and the Lich is that while rat extermination is important, the best method is not to bring food to the breeding grounds... in other words, not to flush things that become rat food into the sewers. However, that's only if rats are the target. If rats completely disappear from the sewers, there's a possibility that house centipedes and cockroaches might turn into monsters, and the damage to humans in that case is unpredictable.
"At the very least, they wouldn't be opponents that three amateurs like us could go to exterminate."
It's as Beatrix says. House centipedes that stick to walls and ceilings and attack soundlessly—we couldn't have won against those when we first started as monster exterminators. We won because they were rats.
"And one more thing. It has been found that rats completely lack parasites like fleas, mites, and lice that are normally attached to ordinary rats. To be precise, if a parasite sucks the blood of a monsterized rat, it dies. As you know, some of those parasites attach to humans and cause harm. At the very least, if monsterized rats are in the sewer, ordinary rats aren't there. Monsterized rats, as a result, also prevent the sewers from becoming a hotbed for parasites."
Mary, who hates things like fleas, is delighted. She might become a fan of rats.
Furthermore, Eleanor-sama raised doubts about the saying that monsters carry plagues. However, she and the Lich aren't certain. The way to check is simple. Just as people keep dogs and cats, they should live with rats...
"That's right. The staff here are in contact with rats on a daily basis. However, no one has contracted a plague. And, at least in Sertoria, in towns with sewers of a scale where monsterized rats can be confirmed, the number of plague victims is lower compared to towns and villages that don't have them."
In other words, are the rats protecting the town? We all looked at each other involuntarily.
Eleanor-sama says that Nakanohara Town in particular has few cases of plagues spreading. The water and sewage systems are well-maintained, and the town itself is on a plateau and isolated in a sense. The only places connected by plains are the southern border and Higashinohara, and the border is separated by a forest. Since the country it borders is Engrio, interaction is close to minimal. Not to mention, people coming from Engrio are strictly checked. Every country is the same, but plague patients are turned away.
"The connection between rats and plagues isn't well understood. It has long been known that the spread of plagues is low when water and sewage systems are well-maintained. However, the possibility that monsters are involved in plagues might be low."
Eleanor-sama says that my magic has established a method to see the black dots that are the cause of plagues. In the future, research into the connection between monsters and plagues might be further advanced.
Magdalena-sama must naturally know this, and she will probably propose a survey of the actual situation in other countries at the next meeting. Every country has towns with well-maintained sewer systems. I've stopped by the capitals of all the countries on the White Island so far, and all the capitals had sewer systems. I don't know about other towns, but at least one location is maintained in each country. If we investigate, we might find some results.
"Then, do we not have to exterminate the rats?"
Beatrix asked.
That's the problem. What was everything we've done until now for?
"No, that's not it. You've seen the tragedy at Stephens' fortress, haven't you? It would be terrible if Nakanohara became like that."
Not only did giant rats grow, but the food at the fortress was devoured. Every town and village should have food stockpiled in preparation for war or famine. It would be terrible if that were taken by rats. Nakanohara in particular has fortresses everywhere for the villagers to evacuate to in preparation for an invasion by Engrio, and they usually store food underground. They must be doing regular rat extermination too.
"That's how it is. We must protect our own food from rats. And, with conventional methods, we cannot eradicate rats. In other words, until there's some new discovery, I think the status quo is fine."
Come to think of it, I remember being told something similar by Adolf-san when we first started rat extermination.
"I see, that's good."
"I'll be counting on you from now on too."
Eleanor-sama smiled.
"Well, I guess we'll just keep playing cat-and-mouse while getting paid."
So said Beatrix, shrugging her shoulders. That was when...
"Come to think of it, rat extermination and the resurrection of the Demon Lord might be similar."
It was Will. The story had become grand in scale.
"In the sense of it being a cat-and-mouse game, yeah."
Beatrix replied. However, perhaps thinking that wasn't all, she peered into Will's eyes as if to prompt her to speak, saying, "Well?"
"Umu. But is that all? In sewers where there are rats, the mice that carry parasites disappear. Could the resurrection of the Demon Lord and the activation of the demon race and monsters that accompany it also have some meaning for humans?"
It had become a difficult topic. Everyone fell silent and looked at Will.
"Wilhelmina, why do you think so?"
Eleanor-sama asked.
"According to the spirits, everyone living on the White Island has some kind of role, and this should apply to the demon race as well. Next, rats devour human food, but at the same time, they prevent the spread of parasites. And rats normally control their breeding numbers themselves, but if food becomes abundant, a massive outbreak occurs temporarily. However, when that happens, they are naturally attacked by external enemies... probably their greatest enemy, humans, and their numbers are significantly reduced. Please try applying these things to the relationship between humans and the demon race. It seems there are commonalities."
Commonalities... I feel like there are, and yet not...
"Does it mean the Demon Lord resurrects if food is abundant?"
I don't really know what the Demon Lord eats. Mana... I feel like that's not it. According to the Dragonewts, mana is thinning out from the entire White Island.
What's increasing... could it be humans?
However, Will shook her head left and right at my question.
"It's the opposite. Don't apply the Demon Lord to the rats; apply humans to the rats, and the Demon Lord to the humans."
I was speechless. What on earth was she saying?
"In other words, are you saying the Demon Lord is reducing the number of humans that have increased too much?"
Eleanor-sama said with a dead serious face.
"Yes. I heard that on this island, unlike the mainland, the islanders are protected from plagues and famine by the Goddess they mostly believe in. In other words, compared to the mainland, there are few triggers for mass death other than war. To that extent, humans might increase too much."
The role of carrying out the slaughter of humans to reduce the number of humans that have increased too much falls to the resurrection of the Demon Lord... That is the Demon Lord's role... If so, the one who gave him that role is...
I involuntarily looked at Harris-sama, who was looking at Henry-sama. Henry-sama also looked at Harris-sama.
When I looked at Harrison-san, he was looking down.
"Eleanor, Wilhelmina. It's a very interesting idea, but it's not good to speak of it to the outside world any further. We might talk about it in secret again sometime. Until then, keep quiet. Everyone else too, understood?"
It was Henry-sama.
He usually says that the Demon Lord's purpose might be the slaughter of humans. He wasn't flatly denying Will's idea.
"Understood."
"I comply."
Eleanor-sama and Will replied, and the conversation ended.