A full week had spun past since Raid-kun and Jan-san had their little mock battle. Now, here I stood, right near the Adventurer's Guild.
It was all the way across town from the West Gate, the one Ron-san and Mile-san guarded so diligently. The Guild nestled close to the East Gate, and less than a minute's easy stroll from that was a huge, wooden building—it looked like a mountain cabin that had somehow eaten a few more mountain cabins to get bigger. As I approached, a few of the craftsmen, whom I now knew by face, gave me a friendly shout.
"Shin-san, how's this look, eh?" they called out.
"Ah, yes. That will be perfectly fine," I replied.
To be honest, I hadn't the foggiest notion of whether it was 'good' or 'bad,' but it certainly looked sturdy enough to house livestock. That, at least, was verifiable.
"Right, then, everyone. Please, release the birds you've caught inside."
At my signal, four adventurers, along with Gil-kun, Luce-san, and Lieben-san, each released the birds they were carrying into the structure. All told, it was about twenty birds, two or three per person. Inside, there were simple nesting boxes, enough room, I calculated, for perhaps a hundred birds.
"Only this many in a single day, I suppose. I was hoping for closer to sixty birds, which means we'll have to do this for two more days, won't we?"
Yes, indeed—this gigantic structure was a bird rearing shed.
The tale of why I felt the need to construct such a thing takes us back to three days before that mock battle.
* * *
"Shin-san! The Count Doorn has sent his gifts of thanks!"
I'd come to the town mansion of the Count Doorn's personal merchant that day to confirm and collect the presents—the promised bounty for my simple dried fish. Carman-san greeted me, and he wasted no time showing me the treasures:
"Alcohol, salt... oil... and is that vinegar?" I inquired, my eyes widening slightly.
I'd assumed that oil and vinegar existed in this world, but to actually see them with my own eyes was a genuine delight. Vegetable oil, I knew, was relatively easy to make from oil-rich fruits like palms; you simply boiled the fruit, then crushed or squeezed it. If you didn't mind the labor, you could crush it patiently with a mortar and pestle, then strain out the impurities with a cloth—no complicated machines needed.
As for the vinegar, I'd bet on its existence. A world with wine, even the crudest kind, was a world that could have vinegar. Wine is the easiest alcohol to make: you crush grapes with their skins, let the natural yeast on the skins ferment the sugar, and voilà, you have alcohol. If you then leave that wine uncovered, it re-ferments with the acetic acid bacteria¹ in the air, creating vinegar—or what we would call wine vinegar. My knowledge was basic, but the logic held: where there is alcohol, there is vinegar.
Lined up before me were two jars of salt, three of oil, and a single jar of vinegar—each about the height of a two-liter bottle. The rest were various kitchen tools.
"Thank you so much. But... this must have cost quite a bit. What is the going rate for these?"
"Well, now. The salt would be ten silver coins per jar, the oil about five silver each. But the vinegar? Only about five copper coins," Carman explained, bowing his head respectfully.
"Eh?" I couldn't help but ask. Vinegar was that cheap?
"Ah, yes. While it is a seasoning, it's generally thought of as a by-product of alcohol, or worse, a spoiled batch. Something of a mistake, you see."
Hm. That's its low standing, is it? Well, I was grateful for it, regardless.
"The most expensive item, of course, is the alcohol. This one item, fetched from the Royal Capital by the Count, would fetch ten gold coins," he announced, his voice puffed up with pride.
It was a generous gesture, but I'm not much of a drinker myself. I suppose I'll share it with the Guild folks later.
"And about that... the Count was wondering if you might be willing to increase the volume of your dried fish trade. Oh, purely at your discretion, of course! No pressure at all, Shin-san."
I'd expected that. Something that costs five silver to produce and can be sold for five gold is a commodity that no amount of supply could satisfy.
"Let me see. Currently, I provide twenty dried fish and about ten birds per week... I understand. I will add an extra ten dried fish and five birds to the weekly trade."
"Birds as well? Thank you! I shall certainly pass that on."
I still had over three thousand gold coins saved up, but lately, I'd had a lot of expenses. The birds, in particular, were now a necessity to keep the business ticking over.
"So, um... might I borrow a cart or something to transport this?"
"Ah, if you're taking it with you, just tell me the destination and we'll arrange the delivery here."
"Very well. Please send it to the Inn 'Clan.' And tell the Count I send my thanks, and that in the future, I will pay, but I'd appreciate it if you could continue to arrange for seasonings and other goods."
He bowed and then strode into the back room to arrange the transport. When he returned, I was already standing, and he bowed again before saying,
"Then, please wait for it at the Inn. And also—"
"? Yes?"
"Well, I just heard that you were the one who negotiated to increase the days of that foot-stomping dance! I am truly grateful! I go every single day while I'm in this town! It's been such a help!!"
Well, more customers is always a good thing for me, too. Especially from a merchant; the tips are probably quite substantial.
* * *
And so it was that the salt, oil, and vinegar found a new home in the kitchen of the Inn 'Clan.'
"You say we can use a little of it? Are you sure? This is such a luxury!" Clara Age-san, the proprietress, inspected the salt and oil, her eyes full of disbelief.
"Huh? Don't you already have salt?" I asked.
"Salt that costs ten silver coins a jar would put me in the red! We use the two-silver kind here, at most. And this oil? The quality is a world apart."
Ah, so there was a big difference. Well, it was a gift from a noble, after all.
"What about the vinegar? Don't you use that?"
"I'm no fancy noble! I can't serve food seasoned with vinegar here."
She had a point. I'd been here for four months, and I hadn't seen a single sour dish.
But salt, oil, and vinegar... with these, and one more ingredient, I knew I could make The Thing.
"Um, are bird eggs sold anywhere?"
"Bird eggs? Such a luxury item wouldn't be found in a town like this. If I ever got my hands on one, I'd eat it myself!" Clara Age scoffed.
I knew it. This was all going to plan, so I wasn't surprised. Even the birds themselves were hard to source, so the eggs would be even rarer. That meant I would have to procure them myself.
I figured I'd wait until Raid-kun's boomerang training was finished, but then the mock battle happened, and I managed to secure the land for the bird shed and hire the craftsmen. Yet, I couldn't refuse Jan-san's request to teach the boomerang to others, so I ended up training five wind-magic users alongside Raid-kun. One of them was Lieben-san, whom I often hired.
The boomerang could be used by anyone, not just wind-magic users, but since I'd created that rule, I had to stick to it. So, a squad of five new boomerang users, including Lieben-san, were selected from the Bronze-class adventurers and trained. Since wind magic itself is incredibly rare—the ability to use Wind Cutter alone could get you to Gold-class—they didn't all get Silver-class promotions like Gil-kun and Luce-san. Instead, they were contracted to serve under Raid-kun's command as a boomerang unit for town defense when needed, for which the guild paid them two gold coins a month. Feeling a sense of obligation, the Boomerang Squad began to prioritize my personal requests.
The first of those was this 'Bird Collection.'
Gathering too many at once would likely destroy the ecosystem, so I expanded the hunting area to the forest across the river, taking Gil-kun, Luce-san, Lieben-san, and four other adventurers with me. I'd hoped to collect some before the shed was finished, but the construction had been unexpectedly delayed—primarily because I insisted on installing a drainage system inside.
The floor was paved with stone, built with various steps, and on top of that, I placed nesting boxes that mimicked nests. The boxes were lined with grass and had opening lids so we could check for eggs. Long branches were also arranged outside the boxes like perches, giving the birds only two comfortable places to rest: the perches or the nest boxes. This design ensured that the droppings fell onto the stone floor, which could then be easily washed out with water into the drain. Wild animals are not known for their hygiene, and birds are notoriously omnivorous, or 'filthy eaters' as some say. I used all my knowledge to keep the facility as clean as possible; the last thing I wanted was for my own facility to become a source of disease. Cleaning the drain would be once a day, the nest boxes once a week, and checking for eggs and feeding twice a day. There were still plenty of unemployed Bronze-class adventurers, so I decided to hire them for the job.
"Thank you for your hard work, everyone. Please, let's do the bird collecting again tomorrow."
I bowed, and the four members of the Boomerang Squad waved, shouting, 'Thanks for the work!' and 'See you tomorrow!' as they departed.
Expanding the hunting range meant a long, nearly half-day expedition, so two trips a day was too time-consuming and would interfere with their regular work. One trip a day was the safer bet.
"Since today is a fish day, Lieben-san, would you mind waiting at the Inn? Gil-kun and Luce-san, you two rest up a bit, then join me at the river."
"Understood, same as always."
"Alright, Shin-san, we'll be at the Guild branch then."
After parting ways with them, I stood alone in front of the rearing shed.
"Well, I suppose the problems are still piling up, aren't they?"
The birds we caught looked like oversized starlings or pigeons from my world. And my knowledge of these particular exotic birds was:
* Rearing History: None, naturally.
* Sex Differences: No idea.
* Ecology: Completely unknown.
It was a perfect trial-and-error situation.
Still, the taste was similar to Earth's poultry. I'd kept parakeets as a child and rescued starlings, so I'd have to throw all that, plus my survival and random knowledge, into the mix.
First, the feed. Birds are generally omnivores, so they should eat anything. Vegetable scraps, grains, and potatoes are cheap and should suffice. Even the guts from the fish I dry might work.
Next, the laying rate. Even the pigeons in Tokyo, with abundant food, are said to lay eggs only seven or eight times a year. However, birds also ovulate, so if I include that, they might lay once a month. Assuming sixty birds, half of which are female, I should be able to secure thirty eggs a month. Should. This purely hypothetical calculation was frustrating because if these birds only laid during a specific breeding season, the whole plan would be useless.
But I had to do it. The main goal was securing income for the winter. Fishing and hunting in the depths of winter would be awful, and if the animals hibernated, I'd be completely stuck. Fish farming was an option, but I lacked the knowledge even for Earth's fish, and securing the land and pools seemed less realistic than this bird project.
"For now, I simply have to move forward," I resolved.
I decided to head to the tool shop to procure basket traps for the day's main work: securing fish.
* * *
Three days later, on what counted as a day off, Mel-san visited me.
"Shin-san! I found some!" she announced cheerfully, arriving at the Inn in the evening.
'Found some' meant eggs.
She and Lieben-san had been helping with the dried fish, and Mel-san had heard about the egg collection project from him. After we'd reached our goal of sixty birds, I'd assigned her to the evening feeding and egg-checking shifts. Her pay was one gold coin a week. To keep jobs rotating among the Bronze-class adventurers, I only gave her two weeks out of every four—the cleaning work, though she could use water magic, went to someone else.
"Oh, so these are the bird eggs," I murmured, peering into the basket she held.
Inside were seven eggs, each about two-thirds the size of a chicken egg from my world. Apparently, they had all been in one nest box, meaning a single bird laid that many at once. Being a multi-layer was a happy surprise. The only question left was whether they'd lay outside of a breeding season...
I glanced at Mel-san. Her eyes were sparkling as she looked at me, clearly expecting an 'offering.'
"Ah... I'm sorry. These eggs have a specific purpose."
Her face immediately fell into a comically deep expression of disappointment.
"N-No! I just want to try something out! Could you wait for me a moment?" I quickly interjected.
I called out to the Inn's proprietress as if calling for help.
"Clara Age-san! May I borrow the kitchen for a moment? Also, could you please roast the fish I set aside and shred the meat?"
For this exact moment, I had kept five fish alive, something I usually never did. While the proprietress took charge of the fish, I began my work with the new condiments.
First, I cracked the eggs, one after another, into a bowl-like container. Mel-san watched, utterly fascinated.
"Are you going to cook the eggs?"
"I will cook them, but later. And also—"
In my world, only the yolk was needed to make a richer, more flavorful product, but these were precious eggs. I couldn't afford to waste any part of them.
I whisked the yolks and whites together vigorously, then poured in the vinegar from the Count.
"Wh-wh-what are you doing!?" Mel-san shrieked.
To her, I must have looked like I was actively ruining a luxury ingredient. As I added the oil, her silent, teary gaze seemed to scream, 'Aghh, the waste! The utter, utter waste!'
Ignoring her dramatic distress, I continued to whisk with single-minded focus. The recipe from my home economics class, if I remembered correctly, was about two parts egg, one part vinegar, and seven parts oil. I finished by adding a dash of the luxury salt for seasoning.
"...What is this stuff?" Mel-san asked, staring at the finished product.
It was a complete unknown, a yellow, viscous substance—mayonnaise, the ubiquitous condiment of my world. Now, for the taste test—
Not a chance.
Eating raw eggs is normal in Japan, but that's the result of maniacally thorough hygiene. Birds, being omnivorous, are a host for all sorts of nasty things. Raw meat, raw guts, and raw eggs are absolutely forbidden. Heating is a necessity, meaning the mayonnaise I had just made was not a simple, ready-to-use seasoning in this world.
Luckily, the Count's gift included glass jars, perfect for sealing. I sealed the newly made condiment—about a liter's worth—inside one, effectively trapping it. Once everything was done—my hands thoroughly washed, the tools scrubbed clean—I finally took a breath. Mel-san was staring at the jar as if it contained a dangerous toxin.
"Mel-san, please, never touch this raw. If you do, you must wash your hands completely afterwards," I instructed.
"R-Roger that, sir!" she yelped.
I might have been overly stern, but given this world's medical standards, it felt necessary. Just then, Clara Age-san arrived.
"Here you go. About three fish... say, what in the world is that?"
Even the proprietress had never seen such a thing. I explained that it was a mix of vinegar, egg, and oil. She was stunned, her eyes wide as saucers, and equally surprised to hear it couldn't be eaten raw.
"Ah, yes, raw egg is out of the question. So, what are we going to do with it?"
"Could you mix it with the shredded fish and bake it all together? It needs to be thoroughly heated."
Clara Age-san paused, arms crossed, pondering. "Hmm. If you want to heat the whole thing, steaming might be the better way. May I borrow those cooking tools the Count gave you?"
"Yes, please! Use anything you need."
With the cooking left to the proprietress, Mel-san and I waited nearby. In less than ten minutes, a wonderful smell filled the air, and the dish was skillfully served on a plate and placed on the table.
"How's this? It smells delicious, anyway," Clara Age said.
The dish—a sort of baked tuna mayonnaise—was clearly unlike anything in this world's cuisine. Clara Age-san offered me a spoon, and I took a scoop, placing it into my mouth. The creamy yellow mixture wrapped around the flaky fish like warm cheese, and the egg's texture and taste reminded me of Earth for the first time in a long time.
"It's wonderful! Truly, Clara Age-san, you're a genius. Now, the two of you must try it. What do you think?"
"Yes, please!"
"Don't mind if I do," the two of them exclaimed, diving into the dish.
Their reaction was immediate and loud.
"SO TASTY! Are eggs always this good?!" Mel-san roared with a joyful gasp.
"I cooked it myself, but honestly... this is better than any meal I've made before!" Clara Age-san admitted, thoroughly impressed.
The mayonnaise dish was a smash hit. I felt a wave of relief; the winter income source was secure.
"So, what about this?" Clara Age-san asked, eyeing the jar of mayonnaise. "Are you going to sell it?"
"Yes, I intend to."
The proprietress stared intently at the jar. "...How many eggs did you use?"
"All seven that I brought!" Mel-san blurted out, answering for me.
Clara Age-san immediately grabbed her head.
"You idiot! Eggs here are more expensive than some medicines! When I was in the Royal Capital, I saw one sell for one gold coin! That means the raw ingredients alone cost seven gold coins! Add the oil and vinegar, and no one in this town could ever afford this!"
Mel-san's eyes blinked rapidly, utterly floored by the price. Her income, which was heavily dependent on me (the dried fish and the bird shed work), was currently about ten gold coins a month. That meant seventy percent of her monthly wage had just gone into making this one jar of mayonnaise.
"I never thought I'd be able to sell it for that high a price. This is just a seasoning, you see. Ah—wait a moment," I said, looking around the kitchen.
I spotted the kitchen's pre-made bread.
"I'm going to use this for a moment. If I do this..."
The bread here was almond-shaped and a little hard. Not inedible, but it certainly gave your jaw a workout. It was necessary for preservation, I suppose. I sliced a slit in the middle and stuffed the baked tuna-mayonnaise mixture inside, like a hot dog.
"What about something like this?"
I offered it to them. Mel-san looked like she was about to drool, while Clara Age-san let out a thoughtful 'Oh.'
"That's interesting. Not placed on top, not used as a dipping sauce... is this a dish from your village, too?" she asked, taking a bite.
Mel-san wildly tore off a piece, but Clara Age-san struggled a bit more. She finally managed to chew and swallow a small piece of the hard bread.
"It's so good-ssu!" Mel-san shouted.
"I see. This way, you only need to put a little bit inside, so the quantity of the expensive part is controlled," Clara Age-san mused.
But the hardness of the bread was still a problem, especially for children and the elderly.
"Wait a minute... you steamed this dish, didn't you? Does that mean you have a steamer?"
"It was one of the cooking tools you brought back from the Count. That's what I used."
Good on you, Count! This was the first time I'd truly, sincerely thanked him.
"Then, with that..."
I suggested to Clara Age-san a piece of knowledge from Earth: steaming bread for about a minute softens it right up. Being a professional chef, she grasped the idea immediately and agreed to steam a loaf.
One minute later...
"WOOOOAH!? Is this the same bread?! It's so soft!" Mel-san exclaimed.
"I've been cooking for years, and I'm still surprised! Steaming can make bread this soft?" Clara Age-san wondered aloud.
To me, it wasn't that soft, but it was certainly as soft as the slightly firm bread I ate back home. This would work for the orphanage children.
"If we're going to cook with this... we can make a lot of this bread-based meal, but we'd still have to charge five or six silver coins a piece. It's too expensive to sell widely, though. Hmm..." The proprietress was already thinking of buying it, but the price was a clear hurdle.
"I'd like to see it sold at a price everyone can afford, if possible," I admitted.
"Affordable? We still have to bake the fish and prepare the bread. If you want to sell it for four or five copper coins a piece, then that jar alone would be worth three silver coins, not a penny less."
"Ah, then, one silver coin for the jar," I offered immediately.
Clara Age-san, who had been speaking, stopped dead, Mel-san mirroring her sudden stillness. Clara Age-san gasped, sucking in a big breath, and finally spoke again.
"You! What in the world are you thinking? I heard you built a huge bird shed just for these eggs!"
"That part is mostly advertising, I suppose. I want to sell it cheaply in this town. I already have someone who buys things from me for a very high price, so I can make my profit there. To do that, I need the reputation that this new dish, made with eggs, is delicious."
The three of us—the proprietress deep in thought, Mel-san utterly lost, and me—were huddled in the corner of the kitchen when a voice called out from outside.
"Proprietress! Is dinner ready soon?"
Clara Age-san glanced back at the voice, then turned back to me.
"...Fine! But your terms are so incredibly generous that it's scary. So, from this month on, your board and meals here are free."
"Really!? Th-then, as soon as I get more eggs, I will give Clan the first right of refusal! And you can have what's left in this jar for free, right now!" I exclaimed, adding new terms to the unexpected bargain.
"Hmph... and what do you call this seasoning?" she asked.
"It's called mayonnaise," I said.
And just like that, mayonnaise was successfully introduced to this world. That night, the Inn 'Clan' was packed to the rafters, serving various dishes featuring the new condiment.
Mel-san, naturally, was right in the middle of the feasting.
Summary:
The determined innovator, Shin, successfully secures luxury ingredients (salt, oil, vinegar) from the Count and finally manages to gather the highly-prized local bird eggs. The culinary genius attempts to create the world's first mayonnaise but immediately hits a wall: the staggering gold-coin value of the raw eggs makes the finished product hopelessly expensive. His solution—creating a steamed, soft-bread 'hot dog' with the baked tuna-mayonnaise mixture—proves the dish's flavor and practicality to the savvy Inn proprietress, Clara Age. The chapter closes with a groundbreaking deal: Shin trades the exclusive local rights to his new 'mayonnaise' for free room and board, securing a vital distribution channel while keeping his high-paying nobleman client. The future of winter income now rests on a yellow, creamy condiment and a flock of captive birds.
Character Insight:
Shin is not a hero of strength, but of practical, financial, and culinary innovation. His primary motivation is always long-term security, which he pursues with a relentless, calculating logic that baffles the local inhabitants. Clara Age's reaction reveals her core: she's a businesswoman first, and the quality of the food has to make financial sense. Mel is simply the audience's window into the pure, unadulterated joy of discovery—food is her ultimate driver.
Behind the Scene:
The high cost of eggs and salt is a critical element of the world-building, emphasizing the pre-industrial economy's scarcity. Shin's invention of mayonnaise is a direct use of advanced, common knowledge to circumvent a major financial barrier. The focus on hygiene (the drainage system, the raw egg warning) is essential because in a world without modern medicine, such an innovation would be a massive public health risk otherwise.
T/L:
¹ Acetic acid bacteria: These are the microbes that turn wine (alcohol) into vinegar (acid). The reaction happens naturally when the wine is exposed to air. ↩
Notes:
• Raid - A young, 'normie' adventurer who gets saddled with the job of escorting Shin. He is carefree and friendly but is instantly put on edge by Jandou's ominous warning. He has short black hair, sun-tanned skin, and wears casual adventure gear.
• Jan - The sturdy branch manager of the local Adventurer's Guild. He is short, has muscular build, and gray hair.
• Mile - One of the two gate guards. He's relatively open and friendly towards Shin after their initial encounter. Wears rough leather armor, has weather-beaten face, and strong build.
• Ron - The second gate guard, usually supporting Mile. He is observant of Shin's methods, though he misinterprets them. Wears same as Mile.
• Shin - An average, middle-aged Japanese salaryman who prides himself on his common sense and average abilities. He was forcibly sent to a fantasy world by a God and granted the 'ability' to prevent anything 'outside his common sense' from occurring in his presence.
• Lieben - A tall man Shin hires for his Wind Magic to help create his dried fish product. He has thin, tall frame and slightly tired eyes.
• Luce - A Bronze-class adventurer, also an orphanage graduate and very close friend of Gil. She specializes in Fire Magic, but can only 'manifest' flames without projection. She has flaxen hair tied in a braid at the back, short stature.
• Gil - A Bronze-class adventurer and recent graduate of the local orphanage. He specializes in Earth Magic (Stone Bullet), but its initial power is weak. He and Luce are close, almost like siblings. He has short hair, slender build, and looks unhealthy.
• Carman - The Count's official merchant in the town. A professional, elderly man who quickly recognized the unexpected value of Shin's processed fish.
• Mel - A young girl Shin hires for her Water Magic to clean his catch. She has semi-long hair, and slightly foxy, sharp eyes.