The Shotoku ichibu kin was minted for only part of 1714, making it one of the shortest lived types of ichibu kin. Together with koban, it had a mintage of only 213,500 ryo, of which half is believed to be ichibu. If correct, this would give us an original mintage of 427,000 pieces.
As of April 2021, none have been straight-graded at PCGS, and I haven't found any details-graded pieces either. They are the same size, design, and composition as the earlier Keicho ichibu, a type that was minted from 1601 to 1695 with no fewer than 10 different major and minor types, possibly more.
The Shotoku ichibu was followed by the Kyoho ichibu, a very similar design, size, and composition. All three of these types - Keicho, Shotoku, and Kyoho - are missing the era designator commonly found on the top right of the obverse of gold ichibu that's used to date them. As a result, they look very similar.
Neither English nor Japanese sources do a very good job of explaining how to differentiate between them. I have accumulated images and auction records of over 180 total Keicho ichibu and approximately 21 Shotoku ichibu. Kyoho ichibu are much more common in Japan, and while I haven't catalogued those auction records, I've seen plenty of pictures including a decent number of examples from PCGS. After examining the images, this is how I've concluded they are distinguished.
First, let's look at the types. Below are all of the types that could be easily confused - Keicho old cast, Keicho Edo mint, Keicho Kyoto mint, Keicho Suruga mint, Shotoku, and Kyoho.
First of all, a couple notes about the photos. I have intentionally selected Keicho images that are easily confusable with the Shotoku or Kyoho ichibu. Some are much easier to distinguish, as will be noted below.
On these examples, it just so happens that all of the Keicho examples have the kirimon stamp (the large, round, incuse stamp on the obverses), while the other two do not. This is not consistent across any of the types - you'll find Keicho ichibu without it, and there are both Shotoku and Kyoho ichibu with it.
Finally, it's worth pointing out that this is the best example of a Shotoku ichibu that I've seen by a mile. They are usually in much worse shape and found with many chopmarks. As a result, some of the criteria we'll be using to ID them may be obscured. This is true to a lesser extent for all of the types above, hence the need for so many criteria. In addition, these examples are not representative of every Keicho ichibu out there; that would be next to impossible to display. To attribute a Shotoku or Kyoho ichibu, it needs to meet all of the following criteria; one is not sufficient.
We won't get into how to distinguish between the different Keicho types, because that's a whole topic unto itself (and there's some debate; these examples are based on the calligraphy distinctions that are the most widely referenced). PCGS counts all of the pictured Keicho ichibu as the same type, so it's not critical for a registry set.
Let's start with the obverses.
ONE - Disconnected Strokes
Look at the top of the obverse. The top character has three short strokes on top; for the Shotoku and Kyoho, these should be small and not connected to the next stroke in the character. This immediately rules out the Keicho Edo mint because the strokes are too long, and the Keicho Suruga mint because the last stroke is connected to the rest of the character.
TWO - Wide Calligraphy
The top character on the Shotoku and Kyoho ichibu is very wide. It comes very close to the borders at its widest point. The Keicho Suruga mint does as well, but the Keicho Kyoto mint is always narrow. In this case so is the Keicho old cast, but it varies depending on the example.
THREE - Connection Style
This is the only distinction for the Shotoku or Kyoho ichibu that's widely published in English or Japanese sources. On Shotoku ichibu, part of the calligraphy where the top two characters overlap is combined; on Kyoho ichibu, it's separate. The outlined area represents the same part of the characters.
However, this is only useful for distinguishing between Shotoku and Kyoho ichibu, as Keicho ichibu can be found with both varieties, as shown below (or it can be obscured, as seen on the Keicho Edo mint). Contrary to what these photos suggest, the Kyoho style is more common on Keicho ichibu, but obviously both can be found. As we'll see later, there's also a much more obvious difference between Shotoku and Kyoho ichibu. It's important to confirm that this area matches what it should be for a Shotoku or Kyoho ichibu, but it is not enough to ID either one.
FOUR - Three Dots
Time to move to the reverse. On most Keicho ichibu, all Shotoku ichibu, and all Kyoho ichibu, there are three dots in the top corners. This is important in differentiating between Keicho old cast and Kyoho ichibu, which can be very similar.
FIVE - Ichi Character
Like number three, this is only useful in distinguishing between Shotoku and Kyoho ichibu, but is significantly more obvious. On Shotoku ichibu, the 一 ("ichi") character on the right fully penetrates the dot border. It doesn't just touch it like on the Keicho Kyoto mint example here; it goes all the way through. Many Keicho ichibu will match the Shotoku ichibu for this one.
On Kyoho ichibu, the 一 character is fully separated from the border. Also notice that it has very slight flourishes at the end. The 一 character on the Keicho old cast is also disconnected, but it's a straight line with no flourishes. This can be hard to distinguish until you've seen a lot of examples.
SIX - Triangle in Bu
This is the last one, but I find it the easiest and it's the first thing I look for. Look at the 分 ("bu") character on the left of the reverse. On Shotoku and Kyoho ichibu, a small triangle is formed in the top portion (in green). On Keicho ichibu, two of the the lines are parallel (in green) and there is no triangle.
The Keicho old cast in this group is the closest I've ever seen a Keicho ichibu get to matching the triangle. In fact, this is the only Keicho ichibu I've ever seen that closely resembles the style of the 分 character on the Shotoku or Kyoho ichibu.
If we combine all of those criteria into one (somewhat overwhelming) image, we can see how each piece was ruled out. In the image below, the white outlines match Shotoku ichibu, the green outlines match Kyoho ichibu, and the red outlines match neither. All of the Keicho ichibu have some red, and the Shotoku and Kyoho ichibu are differentiated by the green sections.
So why does it matter? In the US, there are so few auction records for any of these that it's almost impossible to figure out their relative values.
As mentioned earlier, I haven't delved too deeply into Kyoho ichibu yet, but I've analyzed all of the auction records I can find from the past 10-12 years for Keicho and Shotoku ichibu. Below are some summary statistics, all based solely on Japanese auctions. The original sales were of course in yen, converted to USD below.
Keicho Old Cast
26 sales found
Range from $650 to $3,500, with one outlier at $19,100
This outlier is coin aligned, while the standard is medal aligned. Many different types can be found in coin alignment and they always bring a premium regardless of type.
Including all three mints shown above (no major price difference between them)
110 sales found
Range from $220 to $2,600
There are two other major variations of Keicho ichibu, but these are easily distinguishable by extra characters and are not in danger of being confused with Shotoku or Kyoho ichibu. For the purposes of this topic, they're not relevant and have been omitted.
18 sales found
Average $4,200 (without outlier)
Range from $2,700 to $7,300 with one outlier at $21,500 (discussed later)
Sell frequently in Japan
Strictly based on general observations, they seem to go for $300 to $1,000 on average
As you can see, the Shotoku ichibu is by far the most valuable of the group. Even so, I've actually found one auction record from Japan labelled as a Keicho ichibu that unquestionably fits all of the criteria for a Shotoku ichibu.
On the other end of the spectrum, the only US sale record of a Shotoku ichibu is a Heritage sale from 2011 that realized $5,462.50. It came from the Jacobs collection; Norman Jacobs wrote a book on Japanese coins illustrated by his collection, but his book makes no mention of the Shotoku ichibu. It isn't even mentioned as a type that exists. This piece matches four of the criteria above but clearly breaks the other two, making it just a Keicho ichibu. Even so, it sold for $5,462.50.
On what authority do I question Heritage's attribution? Every single Shotoku ichibu that I've seen sold by a Japanese company or used to illustrate a guidebook has followed all of the rules above. No exceptions. If these criteria are correct, then only one of the pieces I've seen sold from Japan as a Keicho ichibu was misattributed. If the Jacobs piece was indeed a Shotoku ichibu, then far more of the Japanese sales of Keicho ichibu I've found would have to be misattributed. I find it much more likely that a US company misattributed one Japanese piece than multiple Japanese companies misattributed many Japanese pieces.
As mentioned at the beginning, there are no effective English guides thoroughly explaining how to differentiate between these types. Hartill shows the calligraphy difference shown in number three here, but nothing else. I've figured out these criteria by looking at different examples, noting the differences, and comparing the types.
Before we wrap this up, let's talk briefly about the outlier for the Shotoku ichibu. The piece that sold for $21,500 is the example I've used here to represent Shotoku ichibu. Notice that it's pretty clearly struck with no chopmarks or counterstamps; this is almost unheard of. I've only found one other example without chopmarks, and it is a lower grade with much worse eye appeal. A "normal" Shotoku ichibu has multiple chopmarks and lower eye appeal. Keicho and Kyoho ichibu are also very often found with chopmarks, but because there are more examples out there, it's easier to find nice examples mixed in.
Having looked through all the auction records of the past 12 years, it's unsurprising that there are none straight-graded at PCGS. I've only seen two that would have a shot at getting a straight grade, and since Japan doesn't rely heavily on third party grading, it's unlikely either will be showing up at PCGS' door any time soon.