All die numbers have been assigned in an attempt to make a rough guess at likely striking order, but this is purely conjecture. The last die in this sequence, A8, has been found paired with a Keicho B die, implying that it was one of the later dies used for Gaku ichibu. Based on this, I've arranged them based on calligraphy style to create somewhat of a progression from narrow, more literal characters to the wider, more stylized characters seen on A8. Up to three examples are shown of each type, dependent on how many have been found.
The diagnostics described and pictured for each die highlight some of the smaller areas that may be helpful in distinguishing between two similar dies. I encourage you to look at the overall calligraphy style and larger differences first, then use these details to differentiate between the most likely dies. They don't cover all differences or diagnostics.
Populations last updated August 22, 2025.
For easier discussion, please reference the diagram below for the numbering of strokes in 光次 (Mitsutsugu). Further discussion of this design can be found here.

Gaku-A3 shown
Finally, there are some elements that are consistent across all dies that I'd like to highlight. While new dies could change this, I would encourage extreme caution if purchasing a piece that doesn't fit these criteria.
While the design for side B was only used for Gaku ichibu, the A design remained the same throughout the entire gold ichibu series. Because of this, counterfeits are more likely to deviate from the Gaku style for side A while still looking correct at a glance.

Stroke 2 is a C shape. It is not curved the other direction, nor does it have a flick at the bottom.

Stroke 3 feeds directly into stroke 4 with no gap between them.

Strokes 4 and 5 are roughly parallel to each other.

Stroke 7 is below and roughly parallel to stroke 5. It is not to the left of stroke 5.

Stroke 9 appears to either come up beside stroke 6 (top) or connect to the end swoop of 6 (bottom). Stroke 9 does not connect to the middle of stroke 6, and stroke 10 is connected to 9, not 6.

At the top of the center vertical line in the kao, there are three horizontal lines crossing it, visibly separate on both sides (may be merged on low grade or poorly struck examples).

This has been referenced in one Japanese auction as "small characters" (小字) and identified as rarer than "large characters" (大字). The same listing used Gaku-A7 as an example of "large characters," though I assume that designation applies to most dies. I haven't seen any references that distinguish between the two, and it may be a new designation. At any rate, Japanese collectors seem to have noticed that this die has much smaller calligraphy for "Mitsutsugu" than others. The strokes are also more separate and easier to connect to the original characters.
Three distinct die states can be found. The earliest state is seen on the left example above; note that the vertical line in the center of the kao has a slight bend to the right at the bottom. The die chip (to the left of strokes 2 and 4, pictured under Diagnostics) is quite prominent, and strokes 1-3 are quite short.
The die was then re-engraved; the same line in the kao is straight at the end, often with the original bend visible to the right. The die has clearly been polished, making the die chip less prominent and the fields more heavily textured. Strokes 1-3 have been redone and are now larger and more distinct.
Finally, while I've only seen it on one example, there seems to be a late die state where small die chips fill the fields. The die chip near the top of "Mitsutsugu" is larger.
Total Found: 6/35 (17%)
Paired with:
Kirimon stamp on:

There are clear gaps between strokes 6 and 9, as well as 11 and 12.

To the bottom left of stroke 2 is a die chip. This example is the re-engraved die state, where this chip is less prominent.

Pieces from the re-engraved die state show clear evidence of re-engraving in the kao.

Based on the example shown on the right, this die seems to have developed a break to the right of stroke 10, as well as a smaller die crack to the left of stroke 4. None of the other examples I've seen have either of these present, and I believe they may represent a late die state.
Total Found: 5/35 (14%)
Paired with:
Kirimon stamp on:

There's a small die chip between stroke 7 and 8. This area is often obscured by the kirimon stamp, and the chip is not always visible in photos based on condition and lighting.

The fields on this die are textured, showing faint vertical lines in multiple places. To the left of stroke 8 is one of the most consistently visible.

In the bottom border below the kao, two dots slightly to the left of the center are merged together.

Identifying diagnostics is difficult when there are only two photos to go on, one of which is very low quality. The left example has a lot of unusual texturing in the fields, but the example on the right isn't clear enough to confidently say whether this is present. The die could have been roughly polished after some examples were struck, resulting in different die states as seen on A1. The diagnostics below highlight more obvious differences than for many dies, simply because the finer details are less certain.
Total Found: 2/35 (6%)
Paired with:
Kirimon stamp on:

Strokes 4 and 5 have a slight upward curve; they're typically straighter.

There seems to be a rough horizontal line between strokes 7 and 8.

Stroke 12 is slightly closer to the dot border than the kao.

It's worth pointing out that all of these examples are very weakly struck in portions of the kao. All gold ichibu were hand struck, resulting in many pieces that show weakness in some portion of the coin where the dies weren't entirely even. This is (typically) a result of the strike and not the die.
Total Found: 3/35 (9%)
Paired with:
Kirimon stamp on:

Strokes 6 and 9 are fully separate with a visible gap between them.

Stroke 12 is much closer to the kao than to the dot border.

In the bottom right corner, below where the kao touches the dot border, there are three full dots (when the bottom border is visible).

The dies used for kirimon stamps are discussed more thoroughly here, but these two share one of the kirimon stamp dies that's easiest to match. A distinct die crack runs from roughly 2 o'clock to 7 o'clock as struck on the left example. This crack is clearly visible on the second piece even with the low quality photo.
Total Found: 2/35 (6%)
Paired with:
Kirimon stamp on:

There's a small, angular die chip coming off of stroke 4.

Stroke 4 and 5 are angled more sharply down than on most dies, and stroke 4 has a slight downward turn at the left end.

The backwards-C-shaped opening on the left of the kao is very large and doesn't merge with the dot border.

As seen for A3, diagnostics are a bit more difficult to pull when only two examples have been found, one of which is very low resolution. In addition, the example on the left has the faintest kirimon stamp I've seen. Most examples seem to have had the kirimon struck over the finished coin, while it was clearly struck first on this piece. The example on the right has the kirimon stamp on side B and is too low resolution to draw any further conclusions about.
Total Found: 2/35 (6%)
Paired with:
Kirimon stamp on:

The right end of stroke 8 doesn't come anywhere close to stroke 6.

Stroke 12 is very long, and the space between the bottom edge of it and the kao forms a triangle.

The top left line in the kao is typically curved, but this die has a hook on the end.

This die is, quite frankly, a mess. There are die breaks all over the place, plus very distinct texturing in the fields, particularly the top left corner. The dots in the border are larger than normal as well. It's possible that an earlier die state exists without many of the diagnostics below, but I haven't been able to find an example.
You may notice an extra dot in the bottom lefthand corner between two strokes of the kao; this is also present on some examples of Gaku-A8 (though not any of the three pictured), and I don't recommend relying on it for attribution.
Total Found: 4/35 (11%)
Paired with:
Kirimon stamp on:

While vertical polish lines are fairly common in this area, horizontal lines are unusual, making this grid very distinctive.

Stroke 7 is typically close to the left end of stroke 5, but on this die it's fully below stroke 5, nowhere near the left end.

There's a large die break on the right border across from where strokes 10 and 12 meet.

With eleven examples found, this is by far the most common A die. The second most common is A1 with just five examples. While a larger sample could always change these proportions, the gap is so large that I'm fairly comfortable identifying this as most common.
In addition to these eleven examples, this die has also been found paired with a Keicho B die, which is discussed at length here. The Keicho pairing implies that it was likely among the last Gaku dies used, hence its place at the end of the list.
Total Found: 11/35 (31%)
Paired with:
Kirimon stamp on:

Compared to most dies, stroke 2 is smaller, more curved, and farther away from strokes 1 and 4.

The straight horizontal line in the kao is very close to the bottom curve.

The kao opening runs into the left border, fully obscuring the bottom dot. There are two dots in the middle, and the upper arm fades into the top dot.
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