Esoteric Buddhism and Swordsmith Rituals

Japanese Sword Smithing Was a "Sacred Profession"

While the production process of Japanese swords appears to be advanced metalwork from a modern perspective, for medieval sword smiths it was ultimately sacred work performed in collaboration with kami and Buddha. The forging workshop (kajiba) was not merely a workshop, but was strictly maintained as sacred space, where sword smiths purified themselves and continued their training while offering prayers to kami and Buddha.

The relationship between Japanese swords and religion is evident from the fact that the places where sword smiths trained were closely connected to shrines and temples. The five Yamato schools, a group of sword smiths from Yamato (Nara), each operated under the patronage and supervision of powerful shrines and temples, and the temples and shrines that each school relied on differed as follows.

Todai-ji and Kohfuku-ji were separate temples and could not be treated collectively as part of the same lineage. Since the swords themselves were offerings to kami and Buddha, and also served as protective talismans on the battlefield, religious legitimacy was essential to their production.

Concrete Forms of Esoteric Buddhist Ritual

As esoteric Buddhism (the secret Buddhism of Shingon and Tendai sects) permeated warrior society from the Heian to Kamakura periods, esoteric Buddhist elements were incorporated into sword-making workshops.

One of the most important rituals was the "furnace opening" (robirakiakiastery. When lighting a new furnace or before beginning the year's first work, sword smiths offered the following offerings before the furnace, and a Shinto priest or the sword smith themselves would recite ritual words.

• Sakaki branches
• White wooden sacred strips (nusa)
• Salt
• Rice
• Sake

This ritual is still inherited by some sword smiths today, and the first heating using tamahagane is treated as a particularly important religious moment.

The influence of esoteric Buddhism is most evident in the Buddhist Sanskrit character (bonji) engravings applied to the blade. The seed character (shuji) "kaN" symbolizing Fudo Myoo and Sanskrit characters representing Kurikara Ryuoo (the dragon king) were engraved on the blade. These were not mere decoration, but functioned as talismans (jufu) conferring spiritual protection on the sword. Kurikara is the dragon coiled around the sword of Fudo Myoo, and through the esoteric Buddhist symbolism of the unified sword and dragon inscribed on the sword, the sword as a weapon was elevated to become a sacred talisman.

Talismans, Auspicious Objects, and the Space of the Forging Workshop

Religious significance was also embedded in the physical space of the forging workshop. Before the furnace, statues or talismans of Fudo Myoo or Inari kami (known as the kami of forging) were often enshrined, and during work the gaze of kami and Buddha was directed toward the space. Additionally, access to the forging workshop was strictly limited, and those considered unclean (particularly women, whom custom forbade from entering) were prohibited from entering. This was a direct application of esoteric Buddhism's concept of ritual boundaries (kekkai) and purity.

The straw ash (warabai) used as a welding flux had meaning that transcended its chemical function as a flux. The ash from burning rice straw, tied to rice cultivation culture, was interpreted as imparting the grace of deities governing bountiful harvests to the sword.

There was also ritual protocol in handling tamahagane. As the highest grade of iron material, tamahagane was treated as "divine metal," and some sword smiths avoided touching it bare-handed. A practice of chanting brief prayers toward tamahagane before forging was also seen in various regions until modern times.

Quenching and Mystical Perception

The most religiously and mystically significant step in the sword-making process was the quenching (yakiire) stage. This process of heating the blade in a furnace and rapidly cooling it in water was the climactic moment where the sword's fate was determined in an instant.

Medieval sword smiths judged the optimal quenching temperature by sensory standards such as "cherry blossom color" or "the color of the sky at dusk." Modern metallurgy defines a precise temperature range of 650 to 850 degrees Celsius, but for ancient sword smiths this was intuitive knowledge that could not be put into words, transmitted from master to apprentice as a secret technique. It was natural that this process was infused with mystical meaning.

There is also a tradition of performing quenching at night. While this has a practical reason—to see the color of the blade (radiated heat color) more accurately in darkness—it also carried religious significance: to separate the process from the "profane" space of day and perform the most important stage within the "sacred" time of night.

Transformation of Forging Rituals After Modernization

After the Meiji Restoration, following the separation of Shinto and Buddhism (the Shinbutsu Bunri edict) and the decline of the sword-making industry due to the sword ban (haitourei), forging rituals underwent major transformations. Rituals heavily influenced by esoteric Buddhism were lost in many regions, and in most places only Shinto elements remained.

Many contemporary sword smiths today practice the kami ritual of furnace opening or brief prayers at the start of work, but their forms differ from workshop to workshop. In sword-making training sponsored by the Japanese Art Sword Preservation Society (NBTHK), spiritual and religious aspects are placed outside the scope of technical instruction, and each sword smith inherits personal customs learned from their master.

Spirituality as Described by Contemporary Sword Smiths

In interviews with contemporary mukansa sword smiths (the highest rank recognized by the Japanese Art Sword Preservation Society; a different system from the designation of Living National Treasure by the Agency for Cultural Affairs, who are recognized bearers of Important Intangible Cultural Properties), there are not a few sword smiths who speak about religious and spiritual aspects. Expressions such as "when standing before the furnace, I become an instrument of kami and Buddha" and "tamahagane is a living thing and must not be angered" are often spoken not as mere metaphors, but as realized truths learned through long years of training.

While forging rituals are disappearing, their spiritual essence—reverence for materials, worship of the furnace's fire, gratitude for the completion of works—continues to live on in the work ethic of contemporary sword smiths. When appreciating Japanese swords, keeping this spiritual dimension in mind allows the sword to appear not merely as a weapon or work of art, but as something that transcends both.