Ishiguro Koretsune KozukaIshiguro Koretsune

periodLate Edo (ca. 1825)
designationNBTHK Tokubetsu Hozon Tosogu Kozuka
mei 石黒是常 (花押)
Ishiguro Koretsune (kao)
dimensions 9.75 cm x 1.4 cm
price -sold-

The Ishiguro school was founded by Masatsune, a student of Kato Naotsune and Yanagawa Naomasa. He took his name from one character of each of his teachers. Masatsune was born in 1760 and his Ishiguro school is a direct offshoot of the Yokoya school, as Naomasa was the best direct student of Yokoya Somin.

The Ishiguro school's style is based in the work of Somin as a result of this, and over time developed its own themes, frequently representing birds and peaceful scenes of great beauty. Their primary material is gold on shakudo, but they took it to flamboyant and gorgeous styles which were distinct from the work of their ancestors in Yokoya.

Though Masatsune was far above average in skill, he trained two extremely and equally talented masters in Masayoshi and Masaaki that would stand at the very pinnacle of Edo period tosogu craftsmanship. During their time the Ishiguro school became quite famous and featured many other highly skilled smiths, including two additional generations of Masatsune, Koretsune, Yoshitaka, Moriaki, Masaharu, Teruaki, Koreyoshi, Yoshitaka, Yoshitsugu, Masaharu, Masahiro, Masachika, and Teruaki. When Masatsune gave out characters of his name to those he taught, he used the Masa (政) character for his students and Tsune (常) for his blood relatives. So in this was we know that Koretsune is among the children of Masatsune.

Masatsune lived between 1760 and 1828, dying at the age of 69. The second generation Masatsune took over the school, but this did not last long and is likely due to his early death. This made Ishiguro Masayoshi the third head master and recorded this fact in his signature. The final master of the school was the third generation Masatsune.

Juyo Ishiguro Koretsune
Juyo Ishiguro Koretsune

Masatsune had what seems to be two sons, Koretsune who was the oldest, and the nidai Masatsune who originally had a name of Masamori. Koretsune did not inherit the school which seems to also indicate an early death for him, possibly before the Shodai Masatsune himself died. No birth and death dates are known for the 2nd generation Masatsune either. So it would seem unusual to have two generations of Masatsune working at the same time, and an alternate explanation for this is simply that Koretsune signed daimei for his father. Or as above, he may not have existed and is a transcription error in later works of the Shodai's original name.

Masayoshi signed into his mei that he was the 3rd generation Ishiguro master on some pieces. So it seems then that Koretsune, then Masatsune first generation, then Masatsune second generation all died in rapid succession. This left Masayoshi standing as the senior student and the inheritor of the school while the third generation Masatsune was too young to do so.

One of the direct students of the first generation Masatsune was Masahiro, who was given the responsibility of training the third generation Masatsune after the deaths of the first and second generation Masatsune. The third generation Masatsune originally had the name of Shigetsune and is the son of the second generation Masatsune. When Shigetsune was old enough he changed his name to Masatsune and took over the Ishiguro school from Masayoshi some time in the middle 1800s as its fourth master. He would work until the Meiji era.

Kinko Tanki
Kinko Tanki

Ishiguro Koretsune

Koretsune was a son of the 1st gen. Masatsune, namely the eldest son of his second wife. His first name was Shūkichi (周吉) and he used the gō Tōgakushi, Shugyokusai (種玉斎), Shuhōsai (種宝斎), Gishinken (義真軒), Kō´untei (高雲亭), Ittokutei (一得亭), Sekkokusai (石黒斎) and Ichiyō´an (一葉庵).

Due to the fact that he was the eldest son of Masatsune, but did not succeed as 2nd gen., it is assumed by some that he died young, i.e. when his father was still alive. So Masatsune´s second son – then still active under the name Masamori – had to be installed as successor. Marcus Sesko - Kinko Kodogu


The earliest reference that illustrates the school is the Edo Kinko Meifu which was written in 1810, during the lifetime of Ishiguro Masatsune. As such it is the most accurate reference for understanding the early Ishiguro school as it would be based on first hand information gathering (i.e. the author could just knock on the door and ask Shodai Masatsune what is going on). At this point in time the school is not as large as it would end up being later and Masatsune and eight followers are listed. In order they appear as:

  1. Masatsune, with early mei of Koretsune [note: shodai]
  2. Masamori, student of Masatsune [note: became Masatsune nidai]
  3. Masayoshi, student of Masatsune
  4. Masatsugu, student of Masatsune
  5. Masachika, student of Masatsune
  6. Masateru, student of Masatsune
  7. Nagayoshi, student of Masayoshi
  8. Masaharu, later student of Masatsune, originally Mito school Yoshinari

In this we can see that the original group of Ishiguro smiths is Masatsune (founder), Masamori (son), Masayoshi (senior student, first follower), Masatsugu (second student), Masachika (third student), Masateru (fourth student), Nagayoshi (first student of Masayoshi), Masaharu (fifth student and recent transfer from the Mito school).

Masatsune is also noted as originally signing as Koretsune.

The Kinko Tanki follows as the next reference work on the school, and in 1839 lists a dramatically expanded roster of smiths. This points to the rapid rise of Ishiguro and its popularity at the time. The first page is mostly devoted to the family of Masatsune with students beginning at Masanaga. These earlier references than modern books, especially the Kinko Meifu being from the time period of the establishment of the Ishiguro school are critical in understanding its structure.

The first son of Masatsune is also named Koretsune, inheriting this name from his father's original mei. Masamori is thought to be the second son of Masatsune. So we have an uncomfortable situation in that Koretsune the first son, is not listed in the school at the time that the second son is active in 1810.

Tokubetsu Hozon Ishiguro Koretsune Kozuka
Ishiguro Koretsune Kozuka Mei

Research Status Quo

There are several possible explanations for the above, including the early death of Koretsune which seems to be generally accepted as having happened. Previously the NBTHK has described Koretsune as the first son of Masatsune as in the following example which is not that old (2016).

Koretsune was the eldest son of the 1st generation Masatsune (政常) and his first name was Shūkichi (周吉). He used amongst others the gō Tōgakushi (東岳子) and Shuhōsai (種宝斎). He and the 2nd generation Masatsune were both making daisaku works for the first master. Unfortunately, Koretsune died at the prime of his life.... Thus this tsuba is a valuable reference for studies on Koretsune, of whom relatively few works are extant, and for studies on the Ishiguro School in general. NBTHK Juyo Nado Zufu 61

More recently however, in the Ishiguro fittings exhibition catalog, there has been an attempt to revise the understanding of the early succession of the school as follows.

  1. The first son of Masatsune is named as Moritsune rather than Masamori. Masamori has been explained in Haynes as being an independent artist and that there were two generations of Masamori. The second generation of Masamori may instead be spurious and the nidai Masatsune was originally this Moritsune. This makes extra sense in that Masatsune is thought to have given the Masa character to his students and Tsune to his sons.
  2. The second son of Masatsune is now believed to be Koretsune. This then explains why he did not inherit the school. Potentially his manufacture of daimei shifted from his father to his older brother, as it is very difficult to separate out first and second generation Masatsune works. That the father died and the two sons continued his style unabated helps to understand why they cannot easily be separated.

Haynes lists Koretsune as dying in 1850 and this would agree with the most recent publication above. If this new theory is not correct, then Koretsune has to be moved back substantially in time and his absence from the 1810 Edo Kinko Meifu is harder to explain.

The two students that Koretsune is noted to have had by the 1839 publication of the Kinko Tanki are Koreshige and Koreo. They may have been absorbed into the students of Masatsune and undergone name changes as a result. Koreyoshi is another student of his who studied under Masayoshi as well who has to appear after 1839. Since the Kinko Tanki is published in 1839, we have a date for the appearance of Koretsune as an independent artist between 1810 and 1839. Since in 1839 he has two students already and he was making daimei for Masatsune who died in 1828, we can understand his appearance to be somewhere around 1818 and so possibly born around 1800.

If Haynes is correct in the 1850 death date, it also agrees with the NBTHK statement that he died in the prime of his life, but this would still be a fairly good work span. So, the lack of signed works does indeed point to his role in making items signed with his father and brother's name Masatsune for the most part. There really is not very much extant with his own signature of Koretsune on them. There are only four Juyo Token to his name, and after looking at Dai Token Ichi catalogs I can only find one instance where any of his works were sold (one of the Juyo tsuba).


Koretsune is one of the more rare of the Ishiguro smiths to get, and is ranked at Joko in the Kinko Meikan for superior levels of skill.

Currently there are nine sets of tosogu that have passed Tokubetsu Juyo from the Ishiguro school, which makes it clear that they are held in high regard. These are divided between Masayoshi and Masatsune. There are another 65 from the school that have passed Juyo.

Ishiguro work is often found in sets of mitokoromono or else in daisho presentation of tsuba, or if lucky in a larger set of soroikanagu. There are at times individual kozuka or menuki to be found.

At the time of its peak, Ishiguro was very popular for its richness, extravagance and beauty. Today the school is as popular as ever with collectors for the same reasons, and is often difficult to find on the open market.

Ishiguro Koretsune Kozuka OrigamiIshiguro Koretsune Kozuka Detail 2

Tokubetsu Hozon Ishiguro Koretsune Kozuka

This kozuka is a very beautifully made item that is a nice addition to any collection, given the rarity of signed Koretsune work. Also this school is famous for its depictions of birds, but this work shows that Koretsune was able to apply his talent toward fish as well. In this it gains some extra interest as showing an extension of the typical style of Ishiguro.

The koi featured as the subject has the typical mixed metals of the Ishiguro school and has fine details right down to sub-millimeter constructions in the iris and pupil of the fish's eye. The ground of the kozuka is in shakudo and is a variation on the chirimen surfaces that Ishiguro used sometimes rather than nanako. In this case it was meant to provide a more suitable backdrop to frame the subject as it is under water, with the kozuka surface resembling the bottom of a clear pond.

The back side of the kozuka has been finished in katakiribori representing ocean waves as well, to harmonize with the subject matter on the front.

As Juyo Ishiguro works are usually prohibitively expensive to obtain (usually starting around $50,000 and working up), there are not many chances at all for more budget conscious collectors to get nice Ishiguro items. Let alone a good quality Koretsune as his works very rarely appear.

This kozuka comes in a custom fit box. It is ranked at Tokubetsu Hozon for its quality and rarity. I really recommend this kozuka.