Katana Serpent Wave Folded Steel Blade Janami Koshirae 蛇濤

Clay Tempered Ushimo-hada Shinken (真剣) |  Serpent Wave Katana: TangGu (湯谷) Folded Steel Blade (折り返し鍛錬刃) + TangGu (湯谷) Janami Koshirae (蛇浪拵)

This katana is forged in Maru-zukuri (丸造) construction from hand-forged and folded high-carbon steel (折り返し鍛錬高炭素鋼). The surface reveals Ushimo-hada (牛毛肌), a variation within the Masame-hada (柾目肌) category, showing fine ox-hair-like straight grain lines. The edge displays a flowing notare (湾刃) hamon, formed through traditional clay tempering (覆土焼入れ / Fukutsuchi Yakiire). The blade is shaped in shinogi-zukuri (鎬造) geometry with an iori-mune (庵棟) spine and a chū-kissaki (中切先, medium-sized tip). The koshirae (拵) features a round steel maru-gata tsuba (丸形鍔), openworked and carved with a serpent motif (蛇図), finished with a deep black patina (煮黒 / Nuriguro). The fuchi-kashira (縁頭) are also steel with black patina, decorated with matching serpent designs to harmonize with the guard. The tsuka (柄) is wrapped in brown silk ito (茶真絹柄糸) over natural samegawa (本鮫皮) ray skin, reinforced with hishigami (菱紙) to form a precise hishi-gumi (菱組) diamond pattern. The saya (鞘) is finished in black lacquer decorated with silver flecks, creating a starry night appearance (星空塗) with a glossy surface. The koiguchi (鞘口), kojiri (鞘尻), and kurigata (栗形) are reinforced with buffalo horn (牛角) for durability. A brown silk sageo (茶真絹下緒) is traditionally tied to the kurigata, completing the elegant and cohesive mounting.

TangGu (湯谷) Folded Steel Blade

This blade is hand-forged (Tezukuri / 手作り) using folded forging (折り返し鍛錬) from high-carbon steel (高炭素鋼), 

Blade Forging Details

• Blade Name: TangGu Traditionally Forged & Folded Maru Blade (丸造, 折り返し鍛錬)
• Forging Method: This blade is hand-forged and folded in the Maru-zukuri (丸造) style from high-carbon steel (折り返し鍛錬高炭素鋼). It is differentially hardened using clay tempering (覆土焼入れ), producing a hardened edge and a tougher, more resilient spine. This traditional process also results in a visible hamon (刃文).
• Materials: High-carbon steel, folded and forged using traditional methods (伝統的手法による折り返し鍛錬高炭素鋼)
• Purpose: Designed for Iaido (non-sharpened), Kenjutsu, and Tameshigiri (test cutting) practice, as well as for collection, display, and appreciation by enthusiasts and connoisseurs.

Blade Specifications

• Blade Length (Nagasa刃長): Approx 73 cm
• Tang Length (Nakago 茎長): Approx. 26 cm
• Width at Base (Motohaba 元幅): Approx. 32 mm
• Thickness at Base (Motokasane 元重): Approx. 6 mm
• Width at Tip (Sakihaba 先幅): Approx. 24 mm
• Thickness at Tip (Sakikasane先重): Approx. 4 mm
• Kissaki Length (Tip 切先長): Approx. 36 mm
• Mekugi-ana (Peg Hole 目釘穴): 1

Blade Characteristics

• Shape: Shinogi-zukuri (ridged blade 鎬造), Iori-mune (flat ridged spine 庵棟), Chū-kissaki (Medium-sized tip 中切先)
• Forging Pattern (Hada 鍛肌): Ushimo-hada (牛毛肌), a variation within the Masame-hada (柾目肌) category — a fine ox-hair-like forging pattern running parallel along the blade, formed through folded forging (折り返し鍛錬) in Maru-zukuri (丸造) construction.
• Temper Line (Hamon 刃文): Notare-style hamon（のたれ刃文）formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）

Special Features and Workmanship

Hi (Groove) Engraving

• Type: Hi-Nashi (樋なし)
• Processing Range: None (No bohi) – Solid blade for added weight and strength

Polishing Work

• TangGu Polishing Levels:
  • Highest-grade shaping polish 最上・成形研磨 
  • Superior rough polish 最上・下研ぎ 
  • Detailed final polish 最上・仕上げ研ぎ 
• Key Features:
  • The surface shows Ushimo-hada (牛毛肌), a variation of Masame-hada (柾目肌), with fine ox-hair-like straight grain lines. A hakuba (刃白) temper line runs along the edge, formed through clay tempering (覆土焼入れ / Fukutsuchi Yakiire). The shinogi (鋒身筋) ridge is mirror polished.

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Maru-gata (丸形) tsuba made of steel (鋼), finished with black patina (煮黒 / Nuriguro). The surface is openworked and carved with a coiled serpent motif (蛇図).
• Fuchi-Kashira (縁頭): Steel (鋼) with black patina (煮黒 / Nuriguro), carved with serpent designs to match and harmonize with the tsuba.
• Menuki (目貫): Set of menuki placed beneath the brown tsuka-ito (柄糸).
• Habaki (鎺): Brass (真鍮) habaki, polished.
• Samegawa (Ray Skin 柄鮫): Natural unbleached ray skin（本鮫皮）under the wrap.
• Handle Wrapping (Tsuka-maki 柄巻): Brown silk ito (真絹柄糸) wrapped with hishigami (菱紙) in diamond pattern.

Saya and Accessories

• Saya (Scabbard 鞘): Traditional-style saya (拵風鞘), reinforced with water buffalo horn at the koiguchi (mouth), kojiri (end), and kurigata (cord knob).
• Saya Lacquer (鞘塗): Black lacquer saya (黒漆鞘) decorated with silver flecks, creating a starry night appearance, finished with a glossy surface.
• Sageo (Cord 下緒): Brown silk sageo (茶真絹下緒), tied in the traditional style

Measurements

• Blade Weight: Approx. 0.7 kg
• Sword Weight (without Saya): Approx. 1.0 kg
• Total Weight: Approx. 1.2 kg
• Overall Length: Approx. 103 mm