Here was my first one ever! The common type. Typical color, Mt. Fuji and cherry blossom, undated but 1945 attributed. The porcelain coins really aren’t precisely porcelain, but a clay mix baked in high heat. Somehow the translation went that way though and the coins carry the name. Their production was at the end of WWII and there has been some debate on various message boards as to whether they circulated officially or unofficially. Most clearly did not, but as one type is much more commonly found, this has been ascribed to it having been out in the wild for a limited time. Or, that the rumor of circulation just a speculation that has been repeated. It’s an interesting little niche, but little literature exists in English, and apparently not much in Japanese either. I probably should do a proper bibliography, but there just isn’t much. But as I have now acquired a small handful, it seems time to organize what little I know. Jacobs and Verumeule mention little and call the coins red fiber, which they aren’t. Sidebar—red fiber refers to magnesite and was used for some of the overseas issues (Manchukuo specifically). J&V also notes ‘similar patters in clay and other such materials exist’. Instead of photos there are drawings—and the 5 and 10 sen illustrations are swapped. --an older set purchased via a Stephen Album auction, a full 1, 5, 10 sen grouping-- The Cummings book describes more varieties and has several photo illustrations for type, but does not claim to be an exhaustive representation. He gives the total mintage of 15,000,000 with dated pieces for 1944 and 1945. All other sources (including the JNDA) only give year 20 (1945) as the official dates. --Another older set of mine and Stephen Album auction win. The 1 sen color is a bit different and has that 'sheen'. One source indicates that all three were not produced at a single mint, and clay content varied-- Then, there is Krause (looking at my 2015), which appears to be using the illustrations from the Jacobs and Vermeule book (though they correct the placement of the 5 and 10 sen). For the single illustrated types shown in J&V regular KM#s are assigned. Content is noted as ‘baked clay’ (vs. the J&V ‘fiber’ or porcelain), with color variations reported. The one sen also is bears the comment ‘circulated unofficially for a few days before the end of WWII in centra Japan’. The 5 and 10 are ‘not issued for circulation. Moving to the pattern section things are even less clear. For each of the 1, 5, and 10 sen denomination there are two assigned numbers, all dated Yr 20(1945), and all are “(1, 5, or 10) Sen Porcelain Numerous designs exist”. With a third one sen number merely Sen Porcelain. They are listed sequentially as Pn74-79, with Pn74A tacked on last. Sadly I doubt there will ever be any more clarity from the Krause catalog over this. It might be ‘fun’ (not) to go through older/newer editions for changes. --One of my recent auction newps, sorry for the odd orientations, but neat as it shows the color variations of a single type. Whether due to content, baking temperature, or perhaps something else such as storage, I don't know.-- Numista has 8 examples, though the photo for one is incorrect (a 1 sen vs. the 10 sen). The comments under the common 1 sen is most complete and references two production potteries as well as the unofficial release. Also notes the different colors, and attributes that to baking temperatures. Unfortunately no source material is given. --Newps from an overseas auction. No 10 sen for me as yet, but I've seen illustrations.-- The JNDA also only shows representative designs, as drawings only, and lists all under patterns without reference specifically to circulating specimens. By the highly technical method of aiming my phone at the page and engaging Google Translate, this is what I get: Unissued 10 sen pottery (10 sen porcelain in English) Manufactured by Matzukazi Co., Ltd. Kyoto City Showa 20 (Manufactured in 1945) Trial Casting Diameter 21.9 mm Grade feldspar 10-15% Ground Powder 85-90% (the name of the company was translated several different ways, the one I chose was reflected in another source). Unissued 5 sen pottery (5 sen porcelain in English) Seto Wade Pottery Co., Ltd. Aichi Prefecture Showa 20 (Manufactured 1945) Trial Casting Diameter 18 mm Grade university (?) clay 90%/Limonite 10% Unissued 1 sen pottery (1 sen porcelain in English) Arita Town, Saga Prefecture, Kyowa Shinko Pottery Co., Ltd and manufactured in Seto, Kyoto Showa 20(1945)** Diameter 15 mm Grade Mimasaka clay 60%, Izumiyama stone 15% Akame Clay 15% Other 105 **Interestingly the coin illustrated is the common Mt. Fuji 1 sen which allegedly or possibly ‘circulated’ for a day or so. THIS entry in the JNDA does NOT include the ’Trial Casting’ kanji. --Also a newp from the overseas auction. Also missing the 10 sen denomination, but I'm just happy I finally got some of the white ones!-- And finally, I stumbled across a 1973 World Coins ‘gold edition’ monthly publication which included a brief article on the topic by Thomas Alvin Norris III. Google does not reveal much, but he was an advertiser in the publication as well. And includes footnotes and references which I was unfortunately unable to track down. He uses the term ‘toka’ for the coins. He gives a lot of details on production planning and a timeline for the Mint’s efforts in producing the coins. In any case, they came about at the latter part of WWII. As metals were needed for war efforts the smaller denomination coins went through iterations of progressively lighter aluminum and eventually tin. The Japanese Mint went looking for more options. Paper was one, but attention was also turned to non-metallic coin options. Porcelain coins were known from Germany after WWI, the notgeld so it was a known option. The Mint officials eventually produced designs and methods to mass produce the coins. Being clay, the task was given to three major potteries that had the size, materials (clay and coal),manpower, and ability to mint to specification. Unlike metal coins a different kind of ‘shrinkage’ had to be accounted for—drying the clay resulted in a 1-1.5 mm decrease in diameter. Production issues such as uneven heating, cracking, sticking together were noted. But the final products were uniform in diameter/thickness, were sturdy enough to be handled, and retained the design features required including concave surfaces and two step rims. Some have more of a sheen which relates to the proportion of feldspar apparently. And color variances are due to relative content per this source. It appears from the Norris article that the color difference was intentional for each denomination and the planned colors ranging from chocolate, to reddish-brown, to red. But also, white and black examples are known as samples. Up to 91 varieties have been noted, but not confirmed by the sources uses. The three factory potteries utilized were in Kyoto, Seto, and Arita. Interestingly each apparently had a unique specific content to the clay, which I suspect was related to availability of local product. The varying content noted reflects the JNDA. Between designing the coins, determining content and specifications, die production and producing the minting machines it took quite some time to ramp up production of the actual coins. Plus some machinery was destroyed. First meetings were held in early 1944, and mass production began in July 1945. According to the Norris article total mintages were: — Kyoto (1 and 10 sen) 3 million —Seto (1 and 5 sen) 2 million —Arita (1 sen) 1 million And because the government wanted to wait until sufficient quantities were ready before wide release, this did not happen as the war ended in August. But this article also specifically states “Although these coins were never officially released, some one sen toka circulated for one day in Osaka”. I wish I could find and read his sources! In any case, most were ground and destroyed, and the rest are what trade amongst collectors. And finally, what do the TPG say? All I could tell from the NGC census is there are two clay 5 sen pieces dated 1945 in slabs. No 1 or 10 sens are in the reports. No photos that I’ve found yet. PCGS has four 1 sen patterns (a couple Pn74 and PN75 and I wish I knew how they decided which was which). https://www.pcgs.com/valueview/1-sen-1869-1958/1945-h20-p1-sen-km-pn74/4834?sn=418415&h=pop https://www.pcgs.com/valueview/1-sen-1869-1958/1945-s20-p1-sen-km-pn75/4834?sn=620838&h=pop https://www.pcgs.com/valueview/1-sen-1869-1958/1945-h20-p1-sen/4834?sn=418414&h=pop three 5 sen https://www.pcgs.com/valueview/5-sen-1869-1958/1945-s20-p5-sen/4835?sn=418416&h=pop https://www.pcgs.com/valueview/5-sen-1869-1958/1945-s20-p5-sen/4835?sn=418417&h=pop and three 10 sen https://www.pcgs.com/valueview/10-sen-1869-1958/1945-s20-p10-sen-km-pn79/4836?sn=418419&h=pop https://www.pcgs.com/valueview/10-sen-1869-1958/1945-s20-p10-sen-km-pn78/4836?sn=418418&h=pop At some point I will try and add a post with some auction listings plus one more set I'm awaiting.