「As well as taking lessons, I am thinking of making an effort to solve the problem of the Ghouls' declining birth rates.」

As Vandalieu told Zadiris this, her eyes opened wide.

「That is... well, a happy thing for us, but... I hope you are not going to propose that we kidnap women of other races and use a ceremony to turn them into Ghouls?」

「Is something like that really possible?」

According to the information circulating in human society that Darcia had heard, Ghouls were capable of doing this, but Vandalieu had dismissed it as a superstition.

「Yes, it is, though we have never done it in this village. The only females of other races we can abduct from this Devil's Nest are probably female adventurers, so the risk is quite high. And even if we succeed, that might cause other adventurers to come and exterminate us and we would have more important things to worry about than increasing our population by one female.」

Ghouls apparently possessed a way of transforming members of other races into members of their own race like Vampires, though it was less effective as it only worked on females. It was likely something that had been designed to balance the race's low pregnancy and birth rates.

But in this village, the Ghouls had not done this before as they had no way to get their hands on females other than adventurers, and they weren't desperate enough to increase their female count as to take that risk.

「But it is true that no children have been born here in ten years. We cannot ask you to make all of the older members of the village young again to maintain the village, boy, so we would be very grateful if you were to resolve this problem. The other villagers and I will be glad to assist you in any way that we can. And since you were able to use【Youth Transformation】, a spell that even masters of life-attribute magic cannot perform, I am sure you will be able to do it.」

It is a task that one would normally think to be impossible, but it was possible that this boy who only turned two years old just recently could do something about this problem. It was now natural for Zadiris to believe this.

「I will try and do whatever I can.」

Vandalieu meant exactly what he said, but nothing more. There was nothing to suggest that he would be able to do it for certain, and his medical knowledge was limited to medical dramas and school lessons from his time on Earth, and whatever he had managed to absorb from the scientists and researchers in Origin.

In other words, his knowledge applied to humans and worked under the assumption that things like ultrasound machines and microscopes from earth and life-attribute magic from Origin were available.

He wasn't even particularly knowledgeable about the field of maternity and gynecology in the first place. In all honesty, he didn't have any confidence.

However, Vandalieu's death-attribute magic had advanced Origin's medical standards so much that even Rodcorte himself had taken notice of it. With that being the case, doing something to treat the Ghouls' infertility wasn't impossible.

「But I have to keep it a secret from Mom.」

Darcia wouldn't approve of her two-year-old son getting involved in such work. Vandalieu experienced for the first time the feeling of a child keeping a secret from a parent.

A month after Vandalieu had decided to do something about the Ghouls' declining birth rates, he was using the blue flames of【Demon Light】to deal with the heat of summer. Vandalieu quickly identified the cause of the Ghouls' low probability of becoming pregnant.

The method he used was to have ten Ghoul men and women「do it*.」Before, after and also during the act, Vandalieu used【Spirit Form Transformation】and【Sense Life】to determine whether their genitalia, sperm, egg cells and organs were working correctly.

TLN*: The verb used here is the most polite way to say "to do", it's pretty much never used in regular conversation

The cause that he found as a result was a simple, basic one.

First, the sperm of the Ghoul males only survived inside the females for around half a day. This was a much shorter duration than those of other races.

Next, the egg cells of the females only lasted six hours after ovulation. Again, this was much shorter than for other races. In addition, their menstrual cycles were similar to other races, meaning that ovulation occurred only once a month.

「In most cases, I guess the sperm or egg cell, or both, die before fertilization. That explains why they can't get pregnant unless they do it every day.」

Ghouls had no way of determining an appropriate timing in the menstrual cycle to try and conceive, so that contributed to the problem as well.

「I see~ That's how it was. But Vandalieu, why do you keep calling baby-making『doing it?』」

「... I'm still at an age where I'm hesitant to say it so frankly.」

Vandalieu was careful to not look at Bilde, who was lying on the bed made of tree branches woven together after having just finished「doing it.」

『I'm sure that on Earth, it would be the subject who finds this kind of research and treatment more mentally difficult than the researcher.』

For some reason, he was in a strange mood. No, he was happy that his work had produced results and he felt even more motivated. But strangely... He felt slightly downhearted? Like he was suffering? Why did he feel like this?

The reason for it was probably the fact that he was researching ways to treat the infertility of cute girls. He hadn't interacted with the other sex on Earth or in Origin, but now he was in this situation in Lambda. It was kind of unfair. Yes, yes, it was Rodcorte's fault, everything was Rodcorte's fault.

「So don't you have to just stop those sperm and egg cell things from dying? Can you do it?」

As Vandalieu contemplated the problem with no expression on his face, Bilde made this suggestion. It seemed that she didn't really understand what sperm and egg cells were, but she was exactly right.

「I can.」

Indeed, lengthening the lifespans of the sperm and eggs was simple. With Vandalieu's death-attribute magic, he could even prolong the life of a fatally wounded person for days. It wasn't difficult for him to keep the tiny sperm and egg cells alive.

「Really?! Then you've solved it, yay~♪」

Bilde sprang up from the bed and cheered, waving Vandalieu around. However, Vandalieu disagreed with her. The method proposed was possible for him, but it was difficult to call it a solution.

A solution required more progress.

「Now then, I want to figure out a way to prevent the miscarriages...」

「But there's nobody in the village who's pregnant right now... Alright, we just have to get pregnant, then.」

Seeing Bilde's dazzling smile, Vandalieu was definitely feeling strange.

As a result of having the Ghouls mate while using death-attribute magic to keep the sperm and egg cells alive, Bilde and the other females soon became pregnant. He clearly felt the life in the fertilized eggs, and Vandalieu had now confirmed that the problem had been that the sperm and egg cells weren't surviving long enough.

And then Vandalieu figured out why Ghoul women frequently experienced miscarriages in the early stages of pregnancy.

The zygotes had low Vitality.

Using【Spirit Form Transformation】, he determined that Bilde and the mothers had no illnesses or anything that could be an external cause. The zygotes simply had low Vitality.

The mothers had high Vitality, and it seemed that their bodies were mistaking the zygotes and fetuses in their wombs as a foreign entity and attacking them.

This was what was causing the miscarriages in the early stages of pregnancy.

And now that he knew the cause, the rest was simple. He would use death-attribute magic again, this time to prevent the deaths of the zygotes and fetuses. He could prolong their lives until they became able to sustain life on their own.

And in the month of December, where everyone's breath turned into white fog in the air, the results finally showed.

「When I told them that everything is okay now, Bilde and the other mothers were really happy. Of course, it's not just the mothers; everyone else in the village is happy as well.」

「Indeed. Because of you, boy, we are now able to welcome new members into our village. I thank you from the bottom of my heart.」

Basdia, Zadiris and Vandalieu had assembled in a pit dwelling.

「They should stabilize now after three months of life extension. Of course, as long as nobody does anything careless.」

As the Ghoul fetuses reached three months into pregnancy, they were full of Vitality. Vandalieu would observe until Bilde and the other mothers safely gave birth, but he no longer had to keep an eye on them every day.

Previously, Ghouls had to ask themselves whether they would get pregnant when they mated, and whether the pregnancy would make it past three months if they did.

「I see. It has been said that Ghouls have never reproduced outside of Devil's Nests, even in ancient times. But now, if things go well, we may be able to live outside the Devil's Nests.」

Monsters thrived in Devil's Nests, multiplying more vigorously than they would if they were living outside the Devil's Nests and their young would also reach maturity more quickly. The struggle for existence was harsh, and no matter how many adventurers ventured into Devil's Nests to hunt them, monsters would always survive.

Ghouls, who were part monsters, also received effects from living in Devil's Nests. The fact that they were receiving such effects and still had declining birth rates had been worrying them.

That was why producing offspring outside of Devil's Nests had been a hopeless thought. That was why Ghouls lived in Devil's Nests that contained monsters stronger than them, even though there were also plenty of monsters that they hunted as prey.

「Now all that's left for me to do is become able to create a Magic Item that allows the use of the spells that prolong sperm and egg cell life and prevent the death of the fetuses.」

「Yeah, we can't rely on you forever, Van.」

Vandalieu had figured out a method of solving the problem of declining Ghoul birth rates, and it was realistic for him to accomplish. However, this had required him to cast spells on the Ghoul women every day.

As Vandalieu planned to go to the Kingdom of Orbaume, he could only do this for a limited amount of time. And... a continuation of the current situation would be mentally difficult for him.

「You are fairly quick to learn magic, but it seems that you are not so proficient at learning techniques like alchemy, boy.」

As Zadiris said, Vandalieu was aiming to learn alchemy, but it wasn't going well.

In Lambda, there are two types of【abilities.】One is the magic of the different attributes. The other is techniques such as alchemy and spiritual magic.

The magic of the attributes is simply one's affinity for attributes and how well he or she can use those attributes. For example, Zadiris possessed an affinity for the light and wind attributes, while Vandalieu possessed an affinity for the death attribute.

Techniques such as alchemy and spiritual magic represent different skills that applying the attributes that one possesses an affinity for in different ways.

For example, spiritual magic is a technique where one communicates with spirits of the desired attribute and transfers Mana to them to manifest an effect.

And alchemy is a skill where one uses Mana and spells to utilize various catalysts to produce medicines and create Magic Items.

As spirits of the death attribute didn't exist, spiritual magic was impossible for Vandalieu, but if he studied alchemy, he would become able to create Magic Items of the death attribute.

In fact, in Origin, Vandalieu's Mana had been squeezed out of him to produce countless Magic Items. Of course, his body had been taken control over at the time; he didn't know the techniques needed to create them himself. The techniques he had learned about from the spirits of the researchers in Origin relied on Origin's high level of science and technology and manufacturing machinery that relied on other Magic Items, so he couldn't apply it here.

That was why he was learning it from scratch under Zadiris's guidance, but it was proving more difficult than【No-Attribute Magic】and【Mana Control.】

「At this rate, I might not leave until the year after next. On another topic, Basdia, are you sure about your decision? Because I'm here for now, you could have a child if you wanted to.」

Unlike Bilde and the other mothers, Basdia wasn't participating in Vandalieu's research and wasn't pregnant right now. Vandalieu had curiously asked her about it since she had wanted to be pregnant so badly, but she had unexpectedly answered,「No, I'm good for now.」

「If I get pregnant now, after you learn alchemy, I won't be able to become an experimental subject for you to test whether the Magic Items you make work or not.」

「Well, I suppose that's true, but aren't you worried about your age and such?」

Ghoul women stopped aging when they first became pregnant. That was why Basdia, who had never become pregnant yet, had the physical appearance of a twenty-five... no, twenty-six-year-old.

Though Vandalieu thought that she was beautiful and still looked young, so she didn't need to worry about it for a few more years.

「Are you sure? The results have already shown that the boy's methods are reliable, and he is suggesting that you have a child as well. And you do not need to be so worried about being an experimental subject later.」

「Mother, it's fine. Van said he doesn't mind my appearance even if I age a few more years.」

「... Those words sounds like the boy is your partner.」

「... That would take over ten years at a minimum, so please don't mind that and get pregnant already.」

There had been a misunderstanding circulating around the village that Vandalieu and Zadiris were in that kind of relationship, but that had been resolved already. Basdia turned her head and gave the two of them a confused look.

「I didn't phrase that right. I'm not thinking of making children with Van. I'm just looking for some kind of compensation for being an experimental subject.」

「Compensation?」

Vandalieu tilted his head in response to Basdia's words. Since he had come to live in this village, he hadn't interacted with a monetary economy at all... though it would be accurate to say that he had never done so in any of his lives.

「Ah, I do want to ask Van to be my partner for my second child.」

「... Isn't this quite a difficult request to make of a two-year-old boy?」

「It's fine; I'll just wait until you're able to do it, Van.」

「Hmm, is that not fine with you, boy?」

「No, it's not.」

Basdia's aging would indeed stop once she became pregnant for the first time. After that, she would stay young, even as she approached three hundred years of age one day. Even if she waited until Vandalieu developed his secondary sex characteristics, her physical appearance wouldn't change.

However, Vandalieu couldn't imagine wanting to make children in his early teenage years.

「There's no way that I could grasp the responsibilities of being a parent in my early teenage years. And I'm not a human in the first place; I'm a Dhampir born between a Vampire and a Dark Elf. I don't know whether it's even possible for me to have a child with a Ghoul.」

「No need to worry; us races born of the goddess Vida are all able to produce mixed-blood offspring with each other.」

「Is that so? That's a relief, Van.」

「Ah, my excuse for reconsidering this idea has vanished.」

The problem was resolved quickly. The knowledge that the elderly possessed was not to be underestimated.

「And anyway, Van, you're a boy so I don't think you need to grasp the responsibilities of being a parent.」

「Indeed; the role of the male is to risk his life outside the village to hunt for food. Raising the child is a woman's work.」

「No, that only applies for Ghouls.」

Vandalieu supposed that this was how harsh Ghoul society was; the fact that Ghoul men had to risk their lives was very inconvenient for them.

「Well, we are Ghouls, after all.」

「I know. But there's no way of knowing whether the child will be a Ghoul or not. It seems that mating with humans definitely produces Ghoul children, but I'm a Dhampir.」

「Ugh, you got me there.」

But even as she said that, Basdia showed no signs of giving up.

「Then I won't ask you to do it as soon as you become able. I'm alright with waiting until you're willing, Van, since you'll probably live much longer than humans. And I might have changed my mind by then, too.」

That last part was clearly a measure taken by Basdia to prevent Vandalieu from rejecting her on the spot, but Vandalieu knew that her mind would never change and gave a reluctant nod as he let out a sigh.

「When that time comes, please be the partner for my daughter, too.」

「Could you please give me a little breathing room? I don't think it's very admirable to be cornering a two-year-old boy like this at night.」

「Hmm, in that case, the father of my great-grandchild would be you, boy. Well, that is fine, too. Ah yes, boy. While you are at it, if I were to have another daughter in the future, could I ask that you be her first partner?」

「What are you saying, mother! Think about your age, you're over two hundred and ninety years old already! Didn't you say that you even had difficulty giving birth to me?」

「Hmm? Well, you are right, but I feel like I have become younger lately. I am sure I would be fine having a few more children.」

「Where the heck did that confidence come from?! Have you forgotten that time two years ago when you couldn't use your magic and were almost captured by adventurers, all because of your age?!」

As Zadiris dropped bombshells one after another with no sign of hesitation, Basdia was flustered as she tried to bring her mother, who would normally be close to the end of her life, to her senses. As she wasn't aware that Vandalieu had reversed her age to the point that her body's physical age matched its appearance, she showed no signs of calming down.

Vandalieu nibbled on a cookie made from acorn powder as he watched them. They are truly mother and child, he thought as Zadiris and Basdia who had been messing around with him earlier were now being messed around by each other. Also, he felt a little satisfied.

And as he swallowed the piece of acorn cookie in his mouth, he realized that this wasn't the time to be messing around.

Vandalieu has acquired the【Spirit Form】skill!

An arrow flew past, grazing Kachia's ear.

「Kachia, the Goblin Archers are aiming at us!」

「Do something, Rikken!」

「Don't ask for the... impossible!」

Five adventurers were fighting some Goblins... some monsters, including Goblins.

Kachia, the female adventurer who had barely avoided the Goblin Archer's Arrow, shouted panicked words. Rikken fired his arrow, but it was blocked by a Hobgoblin acting as a front guard for the Kobold Mage.

Indeed, it was not only Goblins; this group of monsters included Kobolds and Hobgoblins as well.

Monsters don't cooperate with monsters of other races in normal Devil's Nests except in Dungeons. It wasn't unusual for Hobgoblins to be here, as they have a symbiotic