12 Types of Boshi Patterns Found on Japanese Blades
The term “boshi” refers to the temper line on the tip of a Japanese sword. It plays a crucial role in evaluating the blade as different swordsmiths and schools of swordmaking are associated with various boshi types that have evolved over time. Therefore, examining the boshi can provide valuable insights into the blade’s age, origin, and the identity of its swordsmith.
This article explores the different types and patterns of boshi and how each contributes to the blade’s significance and historical context.
Different Types of Boshi and Their Attribution
The boshi is described by its shape and pattern and can be attributed to individual swordsmiths, swordmaking schools, or traditions. For a comprehensive list of attributions based on the boshi, The Connoisseur’s Book of Japanese Swords by Kōkan Nagayama is a valuable reference.
Kōkan Nagayama observes that the patterns of the boshi and hamon in Koto and Shinshinto blades are nearly identical, though this is not the case with Shinto works.
1. O-maru
An o-maru (大丸) boshi is characterized by a large, roundish kaeri (turn-back). A kaeri refers to the portion of the hamon at the tip of the boshi and curves back to the mune (spine or unsharpened surface of the blade).
The o-maru takes the form of a sweeping, large semi-circle, where the top curves around and turns back toward the mune in a broad arc. Also, the width of the boshi is narrower compared to the ko-maru style.
Leading schools and swordsmiths: The o-maru was popular in the Koto times and can be observed in the works of renowned schools and swordsmiths such as the Rai school, Shintogo Kunimitsu, the Ko-Aoe school, the Enju school, and others. However, it is worth noting that the boshi of Shinto-era swords typically had a relatively wide appearance, making o-maru examples from this period relatively rare.
2. Ko-maru
The term ko-maru (小丸) describes a boshi featuring a small, roundish kaeri. In the standard ko-maru style, the top curves around and then turns back towards the mune, forming an arc that runs from the yokote (line dividing the tip from the rest of the blade) parallel to the cutting edge of the kissaki.
Sometimes, the ko-maru style is further classified into:
- Ko-maru agari (rising small circle)
In ko-maru agari, the top of the rounded part is close to the tip of the kissaki, and the upper area of the boshi is narrower than the lower part.
- Ko-maru sagari (descending small circle).
In ko-maru sagari, the top is positioned at some distance from the tip of the kissaki, and the upper area of the boshi is wider than the lower part.
Leading schools and swordsmiths: The standard ko-maru style is associated with Koto-era schools, including the Awataguchi school, the Rai school, Ko-Bizen Masatsune, the Sue-Bizen school, and others.
Suguha (straight) with ko-maru is primarily observed in Shinto blades and also appears in the works of Yukihide and Sadakazu from the Shinshinto period.
On the other hand, komaru-agari is linked to Shinto-era Yamashiro-province swords, while ko-maru sagari is rarely observed in Koto blades, except towards the end of the Muromachi period. In the Shinto era, the latter is mainly seen in Osaka swords, and in the Shinshinto era, it is seen on swords produced in imitation of Osaka Shinto blades.
3. Midare-komi
A midare-komi (乱れ込み) is characterized by the irregular irregular wave-like pattern of the hamon which continues into the kissaki (blade tip) while the kaeri varies from one blade to another.
Leading schools and swordsmiths: In the Koto era, it is linked with swordsmiths such as Gojo Kanenaga, the Awataguchi school, the Rai school, Bizen-province swords, the Aoe school, and others. In the Shinto era, it is associated with the Hirokawa school, Masatsune, and others. In Shinshinto times, the boshi is usually midare-komi, which is linked to the Suishinshi school and Satsuma-province swords.
4. Jizo
A jizo (地蔵) boshi resembles the profile of statues of the priest Jizo. It appears more or less like midare-komi but is sharply constricted above halfway up and has a rounded top.
Leading schools and swordsmiths: In Koto times, it is linked with the Sue-Seki school, the Hasebe school, the Uda school, the Takada school, and others.
5. Hakikake
A hakikake (掃掛け) boshi is characterized by a brush-stroke-like effect. However, when this effect is more pronounced, is usually referred to as kaen (火炎).
Leading schools and swordsmiths: In Koto times, hakikake is predominantly seen in swords crafted by the Yamato smiths and related schools.
In Shinto times, it is often observed in blades by Myoju and Kunimichi.
In Shinshinto times, it is featured in works by Naotane and Yukihide.
6. Kaen
The term kaen (火焔 or 火炎) literally means flame or blaze. This boshi almost looks as if it were on fire due to the abundance of hakikake and nie (large martensite crystals resembling dots or islands) scattered across the tip. Kaen is often seen in celebrated nie-deki blades, where the hamon features visible grainy nie particles.
In his in-depth discussion of boshi, Markus Sesko, an expert in Japanese arms and armor, notes that the kaeri is sometimes referred to as kaeri-gashira, which literally means head in flames.
Leading schools and swordsmiths: In Koto times, it is linked with the Sanjo school, the Awataguchi school, the Rai school, the Masamune school, and others.
In Shinto times, it is associated with Kunihiro, Horikawa Kuniyasu, and Yoshihira.
In Shinshinto, it is associated with Masahide, Naotane, and others.
7. Ichimai
The ichimai (一枚) describes a fully-tempered kissaki. Most of the time, part of the outline of the boshi is still visible in the point area, indicating that the kissaki is not completely hardened. The kaeri can be observed within the mitsukado—the point where the yokote line, shinogi (line running along the length of the blade), and koshinogi (portion of the shinogi in the point area above the yokote line) converge.
Leading schools and swordsmiths: The ichimai style is exclusively found in blades of the Soshu-den and in swords dating from the end of the Muromachi period.
In Koto times, it is linked with the Masamune school, the Sue-Seki school, the Uda school, the Sue-Bizen school, and others.
In Shinto times, it is associated with Yoshihira, Horikawa Kuniyasu, and others.
8. Ichimonji-kaeri
An ichimonji-kaeri (一文字返り) refers to a boshi with a straight, horizontal turn-back. The kaeri extends straight towards the mune and does not run back along the spine, resulting in a flattened-off top of the boshi.
Leading schools and swordsmiths: The ichimonji-kaeri is most commonly associated with the Koto-era Aoe school and swordsmiths Go Yoshihiro and Zenjo Kaneyoshi.
9. Sansaku
The sansaku-boshi (三作帽子) literally means three swordsmiths. It is formed by a suguha (straight) hamon that extends across the yokote into the boshi. It is a type of ko-maru that starts above the yokote.
Leading schools and swordsmiths: The term sansaku-boshi refers to the boshi of the Three Great (Osafune) Masters: Nagamitsu, Kagemitsu, and Sanenaga. A similar style is observed in the work of Tomonari and Chikakage. Also, the Aoe school’s style typically features a pointed top.
10. Mishina
A variant of sansaku-boshi, the Mishina-boshi (三品帽子) features a kaeri that resembles a narrow jizo-style kaeri. The upper part slopes towards a point, and the kaeri is slightly wider. It was often used by swordsmiths in the vicinity of the Mishina school, giving rise to its name.
Leading schools and swordsmiths: As the name implies, the typical Mishina boshi is produced by the Mishina school. However, a similar type is seen in blades crafted by Kunitomo, Kunimichi, Kanewaka, Yasutsugu, and others.
11. Yakitsume
Also pronounced as yakizume, the yakitsume (焼詰め) refers to a boshi without kaeri or turn-back. Instead, the boshi continues directly to the mune. The patterns could be sugu (straight) or midare-komi (irregular).
Leading schools and swordsmiths: The yakitsume has been produced in every province since the earliest period of the Japanese sword, though it is mainly found among the work of Yamato smiths and related schools. In Shinto times, it is seen in the works of the Yamato-den and related schools.
12. Nie kuzure
A nie-kuzure (沸崩れ) literally means nie break. It refers to a boshi with abundant nie (large martensite crystals resembling dots or islands) scattered throughout the kissaki. Also, the heavily nie-laden boshi looks frayed, making it challenging to define its outline. In some cases, no outline can be made out at all.
Leading schools and swordsmiths: A nie-kuzure is often seen on Soshu blades and schools and swordsmiths influenced by the Soshu tradition. These include the Nobukuni and the Hasebe schools, Shikkake Norinaga, and others. In Shinshinto times, it is associated with Masahide, Naotane, Yukihide, Tomotaka, and others.
