Hitatsura — Scattering Tobi-yaki Across the Whole Blade: The Flamboyant Quenching Technique of the Soshu Tradition

Hamon That Burns Across the Entire Blade

Normally, the hamon of a Japanese sword appears only on the edge side. By applying yakiba-tsuchi thinly to the edge and thickly to the mune side, then rapidly cooling, only the edge hardens firmly, and the boundary emerges as the hamon.

However, there are spectacular and intricate blade patterns where the effects of hardening scatter in dots not only on the blade edge but also on the ji (flat surface). This is called "hitatsura". It is named with the meaning of "burning everything" because the entire blade surface appears to be covered with the appearance of hardening.

The Landscape Where Tobiayaki Scatters

The characteristic of hitatsura is that countless spots of hardening called "tobiayaki" scatter in the area above the normal hamon, on the ji portion. Tobiayaki appears as small hardened areas like islands on the ji far from the edge, and their scattered presence creates a glittering appearance across the entire blade.

Furthermore, it is often accompanied by "muneyaki" where hardening enters the mune as well, so the effects of hardening extend to the edge, ji, and mune all together. In contrast to the quietness of suguha or midare-ba, hitatsura is a blade pattern full of dynamism and splendor.

The Technique Originating with Soshu-den

Hitatsura is deeply connected with the style of "Soshu-den" (the Soshu tradition), which was established in Sagami Province (present-day Kanagawa Prefecture) in the late Kamakura period. Soshu-den is characterized by strong nie activity and free-spirited blade patterns, with hitatsura positioned as one of its ultimate expressions.

During the Nanboku-cho period, masterworks of hitatsura were created by swordsmiths descended from the Soshu-den tradition. Afterward, hitatsura continued to be made by swordsmiths throughout the country influenced by Soshu-den and by smiths of later Shinto periods.

Swordsmiths Known for Hitatsura

Particularly renowned swordsmiths known for their mastery of hitatsura are Hiromitsu and Akihiro of Soshu during the Nanboku-cho period. Both are known for their works with hitatsura on wakizashi and tanto, and are regarded as representative figures of the mature period of Soshu-den.

The Hasebu school of Yamashiro during the same Nanboku-cho period is also known as masters of hitatsura, and the National Treasure "Heshikiri Hasebu" (housed in the Fukuoka City Museum), famous as a blade related to Oda Nobunaga, is cited as a representative work of hitatsura.

From the Muromachi period onward, hitatsura continued to be practiced by swordsmiths throughout the country who studied Soshu-den, and copies and attempted works were created in later periods as well.

The Difficulty of Creating Hitatsura

Hitatsura is a blade pattern that requires advanced technique beyond its visual splendor. The core of the difficulty lies in the precise application of yakiba-tsuchi and control of cooling.

To scatter tobiayaki across the ji, one must apply the clay thinly in only the intended positions on the ji area, which normally would not harden, to make the hardening enter. If the clay is applied thickly, hardening will not enter; if thinly, it will. This subtle application must be done across the entire blade surface while achieving the desired appearance—a most difficult task.

Furthermore, hardening the ji means the blade contains many sections that harden firmly overall. Hardened areas are hard, but are brittle against impact. Hitatsura, in exchange for its beauty, lies alongside the danger of brittleness from excessive hardening, and the swordsmith must exercise meticulous control to prevent compromising the blade's integrity.

Key Points for Appreciation

When viewing a hitatsura blade in person, the use of light is key. By holding the blade against a single light source and gradually changing the angle, the outlines of tobiayaki scattered on the ji and the grain-like appearance of nie emerge. Three points deserve particular attention:

• The form and placement of tobiayaki. The swordsmith's conceptualization of clay application is revealed in whether the island-like hardened areas flow in a connected manner rather than appearing random.
• The presence and continuity of muneyaki.
• The activity within the blade—whether sunamgashi or kinsuji harmonize with the hitatsura appearance.

There are also points to watch for. One should distinguish between works where tobiayaki only slightly mixes with midare-ba and genuine hitatsura where hardening extends to the ji and mune. Also, the white appearance standing on the ji called "utsuri" is a phenomenon of the ji surface itself and distinct from tobiayaki, so one should avoid confusing them. Regarding condition, because hitatsura has a large hardened area, it can sometimes be difficult to determine saiha or blade fatigue; when buying or selling, it is best to make confirmation of a certificate of authenticity a basic practice.

Control Behind the Splendor

At first glance, hitatsura might appear to be the result of hardening that "ran wild." However, in reality, it is the product of a carefully calculated technique with highly controlled clay application and heating and cooling. Each tobiayaki, though appearing free-spirited, is positioned under the swordsmith's intentional control.

When appreciating a hitatsura blade, do look carefully at the positions of tobiayaki and muneyaki scattered on the ji. Behind that splendid appearance lies the skill and courage of the swordsmith who dared to apply the difficult-to-control hardening process across the entire surface.

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