Boy Science Detective: The Scarlet Diamond

[You may want to check the warning on this blog's translations.]

Here, as promised, is the short story by KOSAKAI Fuboku (小酒井 不木, 1890-1929), the first of his 少年科学探偵 (shounen kagaku tantei, Boy Science Detective ) stories, 紅色ダイヤ (beniiro daiya, ‘The Scarlet Diamond’), which you can read on Aozora Bunko here. It was first serialised in 子供の科学 (kodomo no kagaku, Children's Science) between December 1924 and February 1925, then collected in book form in 1926. Kosakai’s works are in the public domain almost everywhere, but if you prefer a book, there is an edition of the stories in print. You can see the earlier post for a general introduction.

I’ve put most of the explanations of subject matter in notes at the end this time, partly because some of them would give away the solution to a puzzle if I wrote them at the beginning. I’ll explain one point in advance, as it might help you if you want to play along with the mystery. The story involves code breaking in Japanese, so the Japanese writing system comes into play. Japanese writing has two kinds of characters, the kana, the Japanese syllable alphabet, and the kanji, the symbol set borrowed from China. The relevant kana for this story are the hiragana, which encode the syllables like this:
あいうえお a i u e o
かきくけこ ka ki ku ke ko
さしすせそ sa shi su se so
たちつてと ta chi tsu te to
なにぬねの na ni nu ne no
はひふへほ ha hi fu he ho
まみむめも ma mi mu me mo
やゆよ ya yu yo
らりるれろ ra ri ru re ro
わ wa, ん n, を o.
As you can see, these look quite like western handwriting, made up of few strokes, mostly curved and flowing. The kanji (used for most nouns, verbs and adjectives) are generally more complicated and more angular looking. For instance, the book title 少年科学探偵 that I quoted above is all kanji.

Story and footnotes come after the break. The footnotes look like this[1] and you'll have to scroll down for them I'm afraid, as I can't work out how to make internal page references inside the blogging editor. I realise this is not ideal, especially since you run some risk of spoiling the story for yourself, if you don't scroll fast (using the find function to get to "Footnotes" would get you past the story, I suppose).

THE SCARLET DIAMOND 

 by KOSAKAI Fuboku

The Mysterious Letter

    Let me introduce you to boy science detective Toshio Tsukuhara. Toshio is twelve this year, but he has more than an adult’s intelligence. At six he astonished his father by working out for himself that the inner angles of a triangle added up to two right angles. In his first year at elementary school,[1] he wrote a haiku,[2] which amazed his teacher:

Mustard in flower,
Children on the embankment
Looking through their legs.

In his second year he already had the knowledge of a child graduating from middle school.[3]
    Toshio liked literature, but he was much more interested in science. Try testing him by asking about the construction of a car, straight away he will draw a skillful diagram and explain it to you. Try testing him by asking the size of an elephant’s red blood cells,[4] he will reply on the spot, ʻ9.4 micronsʼ. The model that Toshio made to explain the movement of the planets is patented and used in middle and technical schools. With all this, Toshio broke off primary school halfway and started doing his own study and research.
    Soon after, he happened to become a fan of detective stories, and finally resolved to become a scientific detective. To be a detective you need knowledge of zoology, mineralogy, botany, physics, chemistry and medicine. Toshio put all his energy into studying these subjects, and in less than three years he had mastered them.
    His father had a small laboratory built for him near their house in the third block of Kojimachi.[5] In it Toshio, a childish figure in western clothes, experiments late into the night, peering into microscopes and fiddling with test tubes. This laboratory now doubles as a detective’s office.
    Toshio’s reputation has grown, so that lately people bring cases to him two or three times a day. With his recent success in solving three major cases of labyrinthine complexity, he has, while still a boy, won the name of ‘great detective’. But since the work of a detective means confronting criminals who have no regard for human life, even Toshio was out of his depth when it came to violence.
    That meant that his life might be in danger; but Toshio is one of those people who refuse to give up. So his worried parents, starting this spring, engaged a strong assistant for him. That assistant is me, a third dan in judo.
    At the start Toshio addressed me as ‘Mr. Ono’, but lately he calls me niisan (‘big brother’). That’s how close we are. I am with Toshio from morning to evening. As we walk around he might surprise me by saying something like, ‘Niisan, just now, you were thinking about the Kodokan,[6] weren’t you?’ When I ask how he knew, he smiles cheerfully and gives a perfectly simple explanation of his line of reasoning.
    Toshio’s decision to become a detective actually came from his uncle in Akasaka,[7] who recommended it with unusual force. The uncle was formerly an official in the communications ministry; but the odd fellow was quite wild about detective stories, and retired at only fifty, to spend the whole day reading them.
    This uncle was a rich man and bought Toshio his research equipment without worrying about the high price. In his house was an ancestral treasure, a large scarlet diamond that Tenjiku Tokubei[8] had brought from Siam. This was famous enough to have occasionally been targeted by thieves before now; and his uncle had promised it to Toshio as a reward if he solved the next difficult case.
    Toshio had always wanted it and was waiting impatiently for the next major case to come. But look what happened then: the scarlet diamond disappeared from his uncle’s house, and that was the start of a case that could not be more important for Toshio or his uncle.
    One day in September a letter in a brown envelope arrived at Toshio’s address. As always, before cutting open the envelope, Toshio examined the paper quality, the lettering, the postmark and so on. As there was no sender name on this envelope, he examined it especially carefully, then finally opened it with a knife and used a pair of tweezers to pull out its contents. What came out was a blank half sheet of Japanese writing paper.
    ‘Niisan, try reading this letter!’ Toshio said, unfolding the white paper.
    I made to pick it up, and he said, ‘Oh wait a moment! We have to take fingerprints before we can touch it.’
    But as there was nothing written on it, there was no way to read it if you wanted to.
    ‘Can you understand what’s written there?’ Toshio asked. He sounded very pleased with himself.
    ‘Not a thing.’
    ‘It’s written in alum.’[9]
    ‘Then if we soak it in water we can read it?’
    ‘Mm.’
    Toshio got the fingerprint tools down from the shelf and smeared an eight percent solution of silver nitrate[10] on the edge of the paper. He put it by the window and let the sun dry it. A little later an incomplete black fingerprint appeared.
    ‘Niisan, the camera.’
    I fetched the camera and Toshio quickly took a photo with it. Then, filling a black lacquered tray with water, he spread the paper out over it and immersed it. With that, white letters appeared.
    ‘Toshio, in the near future there is going to be a major theft; but this time even you will not discover the culprit, I reckon.’ Those were the words written there in brush strokes.
    We had received many threatening letters from criminals before this; but there had never been a criminal who announced his theft in advance. Apart from that, as we did not know where the theft would occur or what would be stolen, even Toshio seemed at a loss.
    After a while Toshio said, ‘Somehow, I think I’ve seen this handwriting before. Look at these letters, they’re written by tying a thread next to the edge of the brush’s shaft and suspending it from a height. By doing that, whoever the writing belongs to, it comes out different.’
    Two or three days passed without incident. Then, on the morning of the fourth day, Toshio’s uncle in Asasaka telephoned urgently summoning him. Toshio reacted with shock, and giving me the bag of detective tools to carry, he set off at a run for his uncle’s house.
    When we got there, the uncle, almost out of his mind with waiting, showed us through to the study.
    ‘The fact is, Toshio, yesterday evening someone stole my diamond!’
    ‘Huh?’ Even Toshio, who was always level headed, turned a little pale.
    ‘Since it’s so precious a piece to me and to you, I haven’t turned it over to the police yet. Can you solve it alone?’ Toshio’s uncle asked.
    ‘I’ll do it alone,’ Toshio said with decision.
    ‘Very good. In that case let me tell you the circumstances of the theft,’ his uncle said, and gave the following account.
    The scarlet diamond was always kept in the safe in the study. This morning after breakfast Toshio’s uncle thought he would look at the newspaper in the library. There he found that the safe door was open, and making a shocked guess, he investigated and found that nothing was missing. But when, just to be sure, he opened the bag that held the diamond, to his horror he found no diamond, only a tightly folded piece of newspaper.
    As the safe had a combination lock, only someone who knew the combination could open it. Seeing how the safe was open like that, and the only person that knew it was Toshio’s uncle, perhaps he had forgotten to shut it yesterday. Also, since from examining the doors and windows there was no sign that anyone had got in from outside, that might suggest that the thief was part of the household; but the household was made up of uncle, aunt, maid and manservant. The last two were old and honest servants and there were not the slightest grounds for suspecting them. …..
    When his uncle finished speaking, Toshio told him about the anonymous letter that he had received a few days ago, then he took out a magnifying glass and investigated the safe. As there was one faint fingerprint on the front of the safe, he sprinkled white lead powder to bring it out and took a photograph of it.
    After inspecting the safe inside and out, Toshio closely examined the study windows and the garden and other places. When he had finished, he returned to the study.
    ‘Uncle, where’s the diamond’s bag?’ he asked.
    His uncle took the bag out of a draw and passed it to him. Inside was the piece of newspaper.
    ‘You didn’t put this in, uncle?’
    ‘No.’
    ‘Then it was probably the thief?’
    ‘I suppose so.’
    Toshio carefully opened the folded newspaper. It was a small piece, about two inches by two. Toshio held it up to the light and turned it round to look at the back. Then he said, ‘Uncle, I’ll just borrow this.’
    ‘Of course. Does that mean you’ve got a line on who did it?’
    ‘I don’t know yet. But I’ll find out in a couple of days.’
    Once he got back from his uncle’s house, Toshio immediately printed a photograph of the fingerprint on top of the safe and compared it with the one from the newspaper. The two fingerprints matched perfectly. After that Toshio handed me the piece of newspaper and said, ‘Niisan, do you know what this is?’
    I looked and saw it was part of a domestic news article[11] and the back was an advert. I could not see any special meaning in it.
    ‘Try holding it up to the light.’
    As instructed, I held it up to the light, and found that someone had made holes with a pin in the letters here and there.
    ‘It’s a code,’ Toshio said.
    Let me copy out the article for you marking[12] the letters with pinholes in them:

    「本郷駒込富士前の理化学研究所、近藤研究室で、整色写真化学の研究を行っている花井時雄氏は、これまでの写真と違って今まで不可能と見做された赤をはじめ、黄や緑などに至る迄それらしく白い様に乾板に感ぜしむる事に成功した。それとともに写真術には常に邪魔され撮影者が之を除くことに最もおおく苦心している紫外線をば特有のスクリーンで完全に除くことに成功した……」 

“At the scientific research institute of Komagome-Fujimae, Hongo Ward,[13] in the Kondo laboratory, Mr. Tokio Hanai, working on colour photograph chemistry, has succeeded in reproducing on a dry plate, like black and white, first the colour red, which until now had been given up as impossible in photography, and going on from that yellow, green and so on. Along with this, he has also invented a special screen that completely excludes ultraviolet rays, which are usually a great hindrance to photography and which photographers have only prevented with great difficulty …..”

Code

    ‘Can you read the code?’ Toshio asked me after a little time had passed. I had read the newspaper article several times; but it was just a report on the invention by a researcher in a scientific laboratory of a new method of photography. There was no way it had any connexion with the disappearance of the diamond. I tried reading just the letters that had pinholes in them, but got no sense from that whatsoever.
    ‘Really, I can’t make anything of it,’ I replied.
    ‘If you could solve it just like that, I’d be annoyed,’ Toshio said laughing.
    ‘Well, have you not read it yet?’
    ‘I can’t.’
    Toshio always hates saying things like ‘don’t know’ and ‘can’t’ and only uses them in really serious difficulties; but finding this code so hard he spat the phrase out with a bitter expression.
    After that Toshio snatched the cutting from my hand and stared at it with fierce concentration for about ten minutes. Then finally he said, ‘Niisan, please copy out only the letters with holes in them.’
    I copied out the following letters on a clean sheet of paper:

    を行って
    での写真
    違って今ま
    能と見做さ
    た赤をは
    黄や緑
    至る迄そ
    く白い様に
    しむる事
    に写真術
    影者が之を
    とに最もお
   
    Toshio took the paper I reached him in his hands and looked at it for a while; but then he said, ‘Niisan, this really doesn’t look like a code that can be broken in one or two hours. Well, let’s think about it slowly!’
    When afternoon came, Toshio asked me to investigate what newspaper it was, and from what day, and if possible to bring that newspaper. Hearing that, I felt pretty hopeless. That newspaper cutting was not necessarily a Tokyo newspaper; and I didn’t know if it was one month old, or two. Searching it out did not sound easy.
    ‘What do you want with the newspaper?’ I asked.
    ‘It doesn’t matter what I want with it,’ he said, a little irritated.
    ‘But, I mean, we don’t know what date it’s from, or where. It’s not something I can find out in one or two days,’ I said.
    ‘Don’t be an idiot, niisan,’ he said, his face getting more and more swollen.
    ‘But really, it’s true isn’t it?’
    ‘Niisan, try using your head, just a bit. Even without my telling you, you should be able to manage something like that. Right, here’s the newspaper cutting for you. I don’t care if it’s in Hongo or wherever, go get it quickly …..’
    I thought I had better not oppose him in that bad mood, and more or less fled outside. But when I stopped and considered where on earth I should go, I suddenly recalled Toshio’s words of a few minutes back, ‘I don’t care if it’s in Hongo or wherever’. I slapped my hand against my leg. Wasn’t the article on the cutting about the scientific research institute in Komagome in Hongo?
    Admiring Toshio’s resourcefulness I rode the train to Hongo, got off at Fujimae, walked to the research institute, and visited Mr. Hanai in the Kondo laboratory. Hanai was welcoming and happy to talk with me.
    There was no way I could say I had come about a code; so I told him I had come to talk about the new photographic technique.
    ‘Ah, you saw that Yomiuri Shimbun[14] article, did you?’ he said with a laugh. My heart jumped.
    After that I listend to Hanai’s friendly explanation for about twenty minutes, then took my leave. As I did so, I asked with feigned nonchalance, ‘When did the Yomiuri journalist interview you?’
    ‘Yesterday afternoon.’
    If it was yesterday afternoon, then there was no question that the article must have come out in today’s paper. My thoughts had got that far as I reached the train stop. Across the road was a newsagents. I wheeled round and marched into the shop, where I bought a copy of the Yomiuri Shimbun. When I opened it up, three up from the bottom of the third page, there was the same article as in the cutting
    I was delighted that I had managed to find the newspaper faster than expected. I wanted to hand it to Toshio and see his smiling face as soon as possible. Unfortunately I met with a power outage at Hibiya Park,[15] and by the time I reached home it was around five thirty, with the autumn sun already setting.
    When I opened the door and entered Toshio’s room, he had a pencil in hand and was deep in thought, so that he did not notice my entrance.
    ‘How’s it going? Solved the code?’ I asked.
    Toshio looked up, but his eyes were focused on some far point. Finally he snapped out of it. ‘I haven’t solved it yet,’ he said bitterly. Looking, I noticed five or six western books on cryptography open on the table.
    At that point the telephone rang and I stood up and lifted the receiver; but Toshio, who until now had been slumped over the table, suddenly sprang up as if he’d had some inspiration, and saying ‘That’s it, I’ve got it,’ he danced around the room.
    Even though I called ‘Toshio, telephone!’ to him, it may have gone in his ears, but in the end all he did was catch on to me and swing round like a madman.
    ‘Toshio! It’s a phone call from your uncle!’ I raised my voce.
    When he heard ‘your uncle’, Toshio put the receiver to his ear. As his uncle had a loud voice, I could easily hear it from where I was standing next to Toshio.
    ‘Toshio, have you found out who did it?’
    ‘Not yet.’
    ‘And the code?’
    ‘Just this moment I discovered the key.’
    ‘Just this moment?’
    ‘It was your phone call that gave me the hint, uncle.’
    ‘That’s strange.’
    ‘Strange, you say?’
    ‘What’s the code?’
    ‘I’m going to decode it straight away.’
    ‘You are? Well work hard! I was just calling to see how things were going.’
    ‘I’ll work hard. Goodbye.’
    I too had no idea what Toshio meant when he said the phone call had lead him to the key to the code. When I asked, Toshio ran to the bookshelves, and opened book after book, then after a while he said, with evident disappointment, ‘That’s no good. We don’t have a book with it in it.’
    ‘Shall I buy one?’
    ‘No, Aoki is fine,’ he said. Then he pressed the bell switch on top of his desk. A little later, the student houseboy[16] Aoki arrived from the main house. Toshio wrote something on a piece of paper and handed it to Aoki. ‘Can you buy this book as fast as possible at Corner of Maruyama Bookshop,[17] please?’
    Sitting at his desk he grinned at me and said, ‘I had a really tough day today, niisan. At any rate, as this is a Japanese code, even if I looked in foreign books, I couldn’t expect to understand; and that said, there aren’t any Japanese books on code. I just had to solve it with my own wits. Firstly, I thought it was clear that these marked passages, を行って, での写真, 違って今ま and the others, were each indicating letters, ‘a’, ‘i’ and so on.
    By the way, in these twelve groups, if you look, not one of them is longer than five characters; so I racked my brains to find something with a connexion with five. Firstly I wondered if it wasn’t changed to the Braille code that blind people use; but that uses six, so I gave that up.
    Just as you came back, I’d got to the stage where I was sure that the kana, as kana, stood for one symbol, the kanji, as kanji, for another.[18] At that point we got that phone call from uncle; and I suddenly got it. Can you see it, niisan?’
    ‘Not a thing.’
    ‘But think of a telephone and it should come to you straight away.’
    ‘Eh? What?’
    ‘The kana is “ton”, the kanji is “tsū”.’
    ‘What’s that?’ I understood even less than before.
    ‘Oh really. Morse code!’[19]
    Hearing that, I finally understood. ‘Ton’ meant the dot of Morse code, ‘tsū’ meant the dash. And then I remembered that the letters were all made up of no more than five dots and dashes.
    Here the student houseboy Aoki came in with a little book. On its cover stood ‘Telegraph Code’.
    ‘Niisan, turn the kana to “ton” and the kanji to “tsū”. Quick, write out these twelve groups and find what letters they show, please.’
    With a little effort, I worked them out, like this:

を行って	・－・・	ka
での写真	・・－－	no
違って今ま	－・・－・	mo
能と見做さ	－・－－・	ru
た赤をは	・－・・	ka
黄や緑	－・－	wa
至る迄そ	－・－・	ni
く白い様に	・－・－・	n
しむる事	・・・－	ku
に写真術	・－－－	o
影者が之を	－－・－・	shi
とに最もお	・・－・・	to

 
    After all my trouble in looking them up ‘Kanomorukawaninkuoshito’ didn’t mean anything at all; but when I looked up, Toshio was making the face of someone who’s found a worm in their apple.
    ‘What’s up?’ I asked.
    Toshio hit the desk, ‘Make a fool of me, will you?’ he snarled.
    ‘Huh?’ I said, surprised.   
    ‘Try reading it from the bottom!’
    ‘Toshio kun ni wakaru mono ka’ (“As if Toshio is going to understand this!”)
    Another joke from the thief! All our efforts had ended in this. It was no wonder Toshio was angry.

An Unexpected Culprit

    I was at a loss how I should console Toshio. Then I suddenly remembered my visit that day to the scientific research institute. Till now, caught up in the codebreaking, I had forgotten to tell the important news. Toshio too seemed not to have noticed my omission.
    ‘Toshio, I quite forgot. The fact is, I got the newspaper that had the article from the cutting in it.’
    Toshio took the newspaper I held out to him, showing no great pleasure; but then, when he finally decided to open it, his face suddenly lit up.
    ‘Niisan, thank you!’ he shouted, and a moment later, like when he solved the code, he did a little dance, gripping my head and kicking out with his legs.
    ‘What is it?’ I asked amazed.
    ‘I know who did it.’
    ‘Huh?’ I couldn’t help but regard Toshio’s words with suspicion.
    ‘Ah, I’m so happy.’ So saying, Toshio again ran round and round the room. I had no idea how just by opening the Yomiuri Shimbun he could know who the thief was.
    ‘Who did it?’
    ‘I can’t say now. I don’t want you asking any more today.’
    The next morning Toshio set off, saying he was just going out to post a letter to his uncle. He did not return until around noon. He had said as he set off that he would rather not have me come with him. So I stayed at the house; but I was somehow worried, and was just thinking of setting off to search the neighbourhood, when Toshio came back, smiling broadly.
    Then, before I could ask where he had been, he turned to me and said that this evening at seven the scarlet diamond’s thief would be paying a call, and could I work with all my effort to catch him.
    Going to catch the culprit was strange enough; the culprit paying a visit would be even odder, I thought, and asked the reason.
    ‘Because he has to come,’ Toshio said smugly.
    ‘Why?’
    Toshio silently took a purple bag out of his pocket, then said, ‘Niisan, look in here.’
    He opened the cover of the bag for an instant before snapping it shut again; but inside, no doubt about it, I had seen the glitter of a scarlet jewel.
    ‘The stolen diamond?’ I asked in astonishment.
    ‘Yes!’
    ‘How did you get hold of it?’
    ‘I took it from where the thief had hidden it. That’s why this evening the thief is going to come to get it back.’
    ‘How on earth did you find it out?’
    ‘I’ll tell you this evening once we’ve caught the thief.’
    ‘You couldn’t let me see that diamond just for a moment could you?’
    ‘No way, no way,’ Toshio said, putting the bag away in his pocket with a teasing laugh.
    I tried to think how Toshio could have found out the thief and stolen the scarlet diamond from him. I had no idea.
    The code message had only been that mockery of Toshio. And as far as I could tell, there had been nothing in yesterday’s Yomiuri Shimbun to give a clue to the thief. However much I puzzled over it, I could not find the answer; but knowing Toshio’s character as I did, I thought it was no good forcing him to answer. I made up my mind just to keep on following his orders.
    We ate supper at five thirty. Slowly it came round to six. Outside was already quite dark, and there were few passers by. When the thief came at seven, the plan was for Toshio to open the door and me to spring at him and put him in handcuffs. Seeing how I was a trained user of judo, whoever I crashed into would make no difference; but my heart jumped as I considered what kind of person the thief might be.
    At last the clock struck seven. With that, outside the laboratory we heard the sound of footsteps, then a knock, knock, knock at the door. Toshio signalled to me with a glance, got up and went to open it.
    Shouting, ‘Yaa!’ I fixed my eyes on the man who came through the door and leapt at him.
    ‘What are you playing at? It’s me!’ The man’s voice was one I had heard somewhere before; but as he was wearing dark glasses and had a beard that covered his whole face, I thought he was a dodgy character and wrestled him to the floor. At that the other replied in kind, violently trying to knock me away, so that in moments we were smashing and crashing about in an all out fight.
    Toshio too at this point ran up to thief. He seemed to be doing something. Finally my strength won out. I was just about to put the thief in handcuffs, when Toshio called out, ‘Niisan, no need to do that. Uncle, take off the dark glasses and the false beard!’
    I released my hold, astonished.
    ‘Toshio! What on earth are you playing at here?’ the man said. He stood up, removing the beard and dark glasses. No doubt about it, it was the Asasaka uncle’s face.
    ‘I’m sorry uncle. But I did promise to catch the thief of the scarlet diamond, didn’t I?’
    ‘Well, you did,’ his uncle said with a bitter expression, brushing off dust from his clothes.
    ‘Since you’re the thief, uncle, I just meant to catch you. In return, here’s the scarlet diamond back.’
    With that Toshio took the bag out of his pocket, opened the cover and held it out in front of his uncle.
    As his uncle saw the brilliant light of the diamond, his face changed colour with shock.
    ‘This is the real scarlet diamond,’ he said, taking a bag just like it from the inner pocket of his jacket. He opened it with trembling hands.
    ‘Wha-, it’s a fake! When could it have been swapped?’ Toshio’s uncle puzzled, his eyes on Toshio’s face.
    I had no idea what was going on. For a while, I just stood there dazed.
    ‘Well anyway, uncle, take a seat’ Toshio said. ‘You too, niisan, you take that chair.’
    With that he began, evidently very pleased with himself, to explain the logic of his deductions. ‘Uncle, when you thought of giving me this diamond, you decided to test my abilities, didn’t you? At the start, when I saw that anonymous letter, I thought the handwriting seemed familiar. And then when I took the fingerprint from the letter, that was your fingerprint. I once took father and mother and your prints, you remember? I tried comparing them.
    Then the fingerprint on the safe was yours. So I thought maybe you were the thief; but since it could be that someone had stolen your paper and used it, and since there was nothing surprising in your prints being on the safe, I thought it was too early to decide that you were the thief, especially since that code was puzzling me.
    But when I set myself to break the code, I got a message mocking me. Add that the newspaper cutting used for the code was yesterday’s Yomiuri Shimbun, and I had solid evidence that you were the culprit. As the theft took place the night before last, if the thief had come from outside, there’s no way they could have cut out a piece from yesterday’s morning paper.
    Again, even if the thief was someone from your household, they would hardly cut up your newspaper immediately before you read it. On top of that, as you had been in the communications ministry, uncle, and would be familiar with telegraph code, I finally came to the conclusion that you must be the culprit.
    If you were the culprit, as I thought you had done it to test my ability, I reckoned that if I told you that I had discovered the culprit and asked you to come here, you would come bringing the diamond. With that I wrote a letter to you last night, and this morning right after posting it I went to Ginza and bought a fake diamond and bag. Then I tricked niisan into fighting you, and in the tumult I searched your pocket and switched the real thing for the fake.’
    Toshio’s uncle’s angry face had during this turned to a broad smile, ‘Whoa, I’m just amazed. The scarlet diamond is yours,’ he said. ‘Cutting up yesterday’s paper was careless of me. For the last four or five days I’d been on the lookout for some article with scientific content. That article fitted perfectly and I made the code. Concentrating on the code, I quite forgot the other thing. I hurried to make the phone call and summon you. Even so, young Ono, you really put me through the wringer didn’t you?’
    I felt like I would like to crawl into a hole, if there had been one there, ‘I’m terribly sorry. It was a horrid prank of Toshio’s.’
    ‘But I wrote in the letter that I was going to put you through the wringer.’
    ‘Huh?’ Toshio’s uncle said in astonishment.
    ‘Did you bring the letter?’
    His uncle took the letter that Toshio had posted this morning out of his waistcoat pocket.
    ‘Try reading the letters with pinholes.’
    His uncle opened out the letter and for a few moments held it up to the electric light to read it.
    ‘I see. My attention was on the disguise and I missed this completely,’ he said, passing the letter to me. I give the message in it below, marking out only those letters that had a pinhole in them.

    Uncle, I’ve finally discovered the thief. I’ve succeeded in getting the diamond back. Please come in disguise this evening at seven o’clock. I’m planning a surprise for niisan; anyway do bring the diamond’s bag and this letter. That code turned out to be really brutal. I’ll explain the details to you when I see you. Please forgive me for the hasty writing.

        From Toshio

    Honoured Uncle.[20]

   
    Fitting the letters with pinpricks together gave you, ‘Uncle, this evening I’m planning for niisan to be really brutal to you. Please forgive me.’
    ‘I’m no match for Toshio,’ his uncle finally admitted defeat.
    And so Toshio won the scarlet diamond.

Footnotes

1. Elementary school 尋常小学校 (jinjoushougakkou), the form of primary education used before the second world war in Japan, teaching children from six to eleven. A first year might be six or seven.
2. haiku, a classic and very common form of Japanese poetry, made of sequences of five, seven then five syllables and including one word, the kigo, that refers to the season to which the poet is reacting. The kigo here will be the flowering mustard or rape, pointing to spring. ‘Looking through their legs’ is my translation of ‘matanozoki’, which is not in my dictionaries, but searching for it on the internet turns up pictures of tourists standing with their legs apart and their head bent down to look between them (like this at Amanohashidate), so that the view is turned upside down.
3. Middle school: at this time (according to the Japanese Wikipedia) teaching boys from twelve to sixteen or seventeen years old.
4. elephant red blood cells: the internet thinks that the size is slightly smaller than this. Most modern pages give a size about 9.2 microns, but looking on Google Books for books before 1926 turns up several that give this measurement, e. g. G. A. Piersol, Normal Histology (Philadelphia, ed. 11, 1916) p. 95.
5. Kojimachi, Koujimachi: a wealthy area in the centre of Tokyo, just west of the Imperial Palace.
6. Kodokan: Koudoukan, important judo institute, founded by the inventor of judo.
7. Akasaka: district in Tokyo, just south of Koujimachi.
8. Tenjiku Tokubei: a famous 17th century Japanese traveller.
9. alum: the internet offers various uses of alum for invisible ink. This particular method turns up in nineteenth century books of home experiments, e. g. Endless Amusement (ed. 7, London, 1847) p. 25 ‘Mix alum with lemon-juice. The letters written with this ink will be invisible until dropped in water.’
10. silver nitrate: used particularly for prints on paper.
11. domestic news article: literally a page 3 article, which in England would mean naked women, but in Japan means society, in the sociology sense, not in the ‘high society’ sense: often this means accounts of crimes, in this case it is technological news.
12. marking: in the original the pinpricked letters are marked with a dot (a Japanese print convention for emphasis), but the file from Aozora Bunko loses its dots when you print it; so I thought it might be easier to replace it with something else.
13. Hongo: Hongou, a former ward of Tokyo, north of the Imperial Palace and west of Ueno.
14. Yomiuri Shimbun: one of Japan’s major newspapers, see Wikipedia here.
15. Hibiya Park: a park in central Tokyo south of the Imperial Palace.
16. student houseboy: 書生 (shosei), a student working as a servant in the house they are boarding in, a phenomenon of the Meiji and Taishou periods.
17. For the story, all that matters is that it's a bookshop; I couldn't find what parts were place name (if any) and what parts were shop name (if any).
18. kanji and kana: see the introduction at the start of the post.
19. Japanese morse: uses the same sequences as in the west, but has a system for encoding the Japanese syllable alphabet (see the Japanese wikipedia article).
20. This is the format in the Aozora Bunko file (which is laid with horizontal text, unlike the vertical text normal for books). Vertically printed, the letter would read from right to left, Toshio's name would be at the bottom on the left,  and the address to his uncle would be above it further to the left.