In a Different World with a Smartphone

『There are eight coins and a single scale. However, only one is a counterfeit among those coins. The forged coin is just a little bit lighter than the real thing, and it’s possible to ascertain which is the fake one or which is the real one immediately with the weighing scales. The question is then, what is the least number of measurements necessary to find that forged coin? Furthermore, if you give an incorrect answer, you will be compulsory returned to the entrance 』

This one is a genuine riddle, isn’t it? Well, it does look normal.

It is a problem one can understand if one thinks about it a for short while. The right answer is..... No..... Wait a moment.

I pour magic power with water attribute as I reconsider the answer.

Ding-dong, ding-dong, ding-dong, ding-dong.

Just as I’ve thought! Its true character is difficult....... I glare at the wall that is rumbling as it opens.

『Lord, what is the answer this time?』

Kohaku asks me. N? Aah, haven’t you understood it after it came to your mind?

「If you normally think about it, how many measurements do you think it would take? 」

『The first one is to weigh four coins on both sides of the scales. The second one is to weigh the four coins from the lighter side. We divide those by two and place them on the scales once again. The third and the last measurement would be among the two coins left. The lighter one will be the forged coin. I believe it will take 3 measurements』

「You might say that’s right. However, if you place three coins on both sides of the scales and weigh them and they are balanced, it means that one of the remaining two coins is a forged coin, therefore it will take two measurements. If they are not balanced, you place one coin on each side of the scales from among those that were lighter. If they are balanced, the remaining coin would be a forged coin and if there are not balanced, the forged coin would be the lighter one among those two. It will take two measurements either way. When speaking in general, that’s the correct answer」

In general, that is.

『Does Lord imply it won’t take even two measurements?』

「The answer is that it will take “one” measurement. You take two coins among those eight, and, [If you are lucky] then when you use the scales to measure them, you will be able to find it with a single measurement, right?」

『Saying “if you are lucky”.....』

「The question didn’t designate things like [certainty] or [single try], right? It’s a question asking to answer with the least number of times the scales need to be used 」

Those really are the ruins of Babylon. This question is nasty. It reflects the thinking of that professor. Considering my long-time association with her, I somehow start to understand her thinking.... although I feel somewhat reluctant to admit it.... It feels like I am being covered in filth.

============================Scene-Change=============================

And after that,

『By abiding the rules of the following calculation equations, derive the answer. Please answer with the number which is applicable for “□”』

36＝1

108＝3

2160＝2

10800＝□

As I encounter such a comparatively upfront question, I have some doubts whether there is some hidden trick to it.

In the end, there was no trick to it. The answer was a simple [5].

Either way, this is not a particular type of puzzle, but a regular riddle. Though it’s definitely not hard, It would be troublesome to be sent back to the entrance if I answered those wrong. The wall is closing again, and the riddle changes into a new one. When I briefly look up,

『There are two magic ropes which cannot be cut and when either one is ignited from one side, it will take one hour for that rope to burn out. What’s the best way to accurately measure 45 minutes without preserving any rope?』

『As the man was about to prepare four fish for an evening meal, three cats came by while holding one fish each and ran away. Though there are four members in man’s family, each one was able to eat one fish during an evening meal without any problem. How? 』

『There are 27 gold in the bag. If three adventurers divide them equally, and yet there are at least 5 coins remaining in the bag, what’s the maximum amount one person is able to get?』

Typical riddles. Since I don’t want to return, even as I choose the answer, I reconsider it once more, wondering whether I have overlooked something or if there is some trick to this riddle. Though it has taken some time in the end, I arrived at the feeling that I was dancing at the palm of that professor’s hand and found myself feeling harassed.

Incidentally speaking, the answers to the question from before are,

『Among the two ropes, we ignite both ends of one of them and ignite one end of the other one. When the rope which was ignited from both side burns out, we ignite the other end of the remaining rope. When it burns out, the time it took will be 30 minutes + 15 minutes = 45 minutes』

『The cats are [Holding] three fishes and run away, so there are 7 fishes in total. There is no problem with those』

(TL: a word riddle, “holding in mouth” and “adding” has the same reading of “くわえて”, so it is implied that cats brought more fish rather than took some).

『It is 9 coins. After dividing those equally, one person will take his coins together with bag』

That is what it comes to.

Ding-dong, ding-dong, ding-dong.

As I broke through the last room with no-attribute Hokora, there was a familiar transfer formation which stood on six stone pillars.

「I made it, didn’t I..... After truly taking my time..... 」

Anyway, though it might have been that professor’s prank, it really was some experience for me having to deal with it. While I was already fed up with it, I poured the magic into magic stones in six pillars and stood together with Kohaku in the center of transfer formation. After pouring no-attribute magic under my feet, the transfer formation became activated.

===========================Scene-Change===============================

As the torrent of light fades away and I open my eyes, there is the usual scenery of Babylon. Every tree is being stirred by the wind and the sea of clouds is spreading before me.

While I look around the vicinity restlessly, a building becomes visible on the opposite side of the trees. Now then, is that [Warehouse], [Library], or [Laboratory]?

As I stepped out from the transfer formation and turned in the direction of the building, I immediately understood what that building was from everything I came to see before long.

The building’s shape was similar to a round can of tuna. The entire surface is made of glass, and the inside is completely visible. What comes into view is the interior filled with bookshelves which seem to stretch for who knows how far, and which are furthermore tightly packed with a mountain of books.

It is [Library]. No doubts about that.

Circling around the building’s circumference, I search for the entrance. Soon, We reached a magnificent large door.

As I open the massive double doors, there is one more door in the inner parts as well. After opening it as well, I enter [Library].

「Uwaa......」

『This is......』

Both me and Kohaku are lost for words. There are books, books, and more books as far as eyes can reach. The lined up bookshelves as well are at least 10 meters high, and since the outer wall is drawing a curve at the same time, this place really looks like a labyrinth.

There are books located as seemingly unreachable for hand heights, how am I supposed to take them? There is nothing sort of ladder or stepladder around....

As I tread on the red carpet with my feet, I decide to turn towards the center of this circle for the time being. Since it is built in a complicated form, I cannot go there in a straight line. I suppose that’s an intentional omission in the arrangement of the bookshelves.

Still, when I look at the ceiling, I can understand the direction of the center from the joining points spreading out in a radiating shape, so I continue going by following them.

After advancing for a short while, I see a desk and chair in a sudden clearing. Various books lying on top of the desk have already become a huge pile and a single girl was sitting down on a sofa among that heap.

Having dropped her eyes to the book she was holding, she didn’t even try looking in this direction. Her chestnut-colored hair is cut shortly and her face adorned with glasses looks common to other Babylon Numbers. Her clothes are the same as others as well, so that girl must be the manager of [Library].

「Anoo......」

「I will finish reading this in about 30 minutes, so please do not start a conversation with me」

「Ah, okay......」

How unapproachable. This is definitely the treatment for those considered to be a total nuisance. It can’t be helped, should I wait? Only the sound of pages being turned over by the girl is hanging in the quiet room. Having become bored, I try taking and opening the book from around this area in my hand innocently.

「I can’t read it......」

What language is that? It looks neither ancient magic language nor the ancient language of the spirits. Is that ancient Paruteno language?

「Reading/Ancient Paruteno language」

Ah, I can read it, I can. But...... It is so difficult that I can’t understand it...... It looks like a report from the investigation and inquiry into magic beasts or something.

Is it because [Reading] was invoked, the titles written on the bindings on the books here and there became readable. That must mean that all those books have been written in ancient Paruteno language.

「Inquiry and interference into manipulation of magic fluids」

「Magic herbalism and secret medicines」

「”Introduction into night”, Beginner’s edition」

(TL: I laughed too much at this than I should have)

Oi. As I reached out my hand a bit towards such straightforward title and tried flipping over its pages, it was typical “how-to” book just as one would expect of it.

『In order to be able to enjoy each other, it is better to first of all start with getting rid of the tension. If not underaged, it’s not bad to also borrow just a little bit of alcohol’s power by drinking lightly. However, if the alcohol is too strong, everything will turn into a mess, so it’s better to at least be prudent after all. Next is, the partner’s.... 』

Hmmmmmm.... Ho, hoo...... I~, I see.........

This is unexpectedly.... usable.... I think..... Eh, that is .... Is that so? Well, but still..... The hurdle is high, I guess~. This [casual] thing, it is difficult.....

「What are you reading? 」

「Awaaa ！？」

I spring up instinctively at the raised up voice from behind. You surprised me! Are? Did 30 minutes pass already?

A young girl opens her mouth while tilting her head in my direction looking puzzled.

「Welcome to Babylon’s [Library]. I am the management terminal to this [Library], my name is Irisfam. Please call me Fam」

「Ah, Aah, Fam, ~right. I am Mochizuki Touya. Nice to meet you」

I put back the book into its place with my hand behind me while replying to the girl. I wonder if she saw through that.....

「For you to come here, that means you have solved the professor’s questions, haven’t you? In recognition of the conditions being satisfied, the frame number 24, codenamed [Irisfam], will be transferred to you from henceforth. Please treat me well, Master」

Ah, just as I thought, the one who made those questions is the professor, didn’t she? No one else would need to create them that way one by one. Well, I guess it is still better than just being excessively exposed to ero-attacks..... Haa!

Having realized the following development, I tried to put myself on guard, but it was too late, my lips were snatched by Fam. Quickly thrusting in her tongue, she kept violating the interior of my mouth. In comparison to the time with Liora from [Rampart], she instantly ended this act which she achieved so easily.

「Registration complete. I have collected Master’s genes. From now on, the ownership of [Library] will be transferred to Master」

Kuu, do I really not learn? Despite that I knew it would turn out like this. Well, since I don’t have an option to not do it, I would have to do it sooner or later, and it is better to do it rather the being deceived due to some weird situation, right?.....

「So, that is the status? How many Babylon have been gathered?」

「Eh? E~to, [Garden], [Workshop], [Alchemy Building], [Hangar], [Rampart], [Tower]. The six of those. It will be seven with [Library]」

「I see. Then, let us proceed this way」

As Fam typed something into the desk’s terminal, [Library] quietly came to live. It is probably turning to dock with other Babylon located in the skies above Brunhild.

「Master, I have a request. I would like to receive new books for this [Library].... 」

「Even more books that those already present here? Or rather, there is surely some number of them here」

「I believe that roughly 20 million books have been passed down」

20 mil...... If I am not mistaken, even The Library of Congress in Japan has a book collection amounting to about 10 million items, doesn’t it? Certainly, if you add everything like magazines, newspapers and nonbook materials, it should rise up to about 35 million.

「Since I have read almost all of them, I want to read some new ones. I urgently request this」

「Saying you read them.... All 20 million of them?」

「I read one book in two hours on average, and when one continues to do it for about 5000 years, it will be around this much」

No-no-no. Did you not rest even a single day !? Shizuka and Flora had slept for who knows how many years by using sleep devices, and when I arrived to Noel from [Tower], she was sleeping even then. Are you aware of that !?

「That’s because I do not move much. But still, when you are operating for more than 5000 years, your condition will be poor-looking. Well, once [Laboratory] is found, I should be able to do proper maintenance」

So she has been reading books for more than 5000 years..... She is hardcore book lover, all right. Is she one of those book junkies? How unexpected.

For the time being, shall I report that I have found [Library] which Rin craves for? And since it is Rin I am talking about, she looks like she would stay here for a long time, I suppose.