Katana Blazing Sun Oroshigane Kobuse Blade Jojaku Koshirae 炎陽

Folded Oroshigane Steel Shinken (真剣) | Blazing Sun Katana: TangGu (湯谷) Oroshigane (卸し金) Kobuse Blade (甲伏造) + TangGu (湯谷) Hantachi Jojaku Koshirae (常寂拵)

The Hantachi-style koshirae (半太刀拵) combines classical design with functional strength. The blade is forged from Oroshigane (卸し金) steel in Kobuse-zukuri (甲伏造) construction, with a hard steel jacket and softer core. The surface shows Ayasugi-hada (綾杉肌) grain and a straight suguha hamon (直刃刃文) created through clay tempering (覆土焼入れ). The saya (鞘) is in hantachi (半太刀) configuration with steel fittings replacing buffalo horn. Palm lacquer (棕櫚塗) gives a textured finish. A golden-brown silk sageo (下緒) is tightly tied. The tsuka (柄) is wrapped in amber silk ito over aged yellow samegawa (鮫皮) with hishigami (菱紙) inserts. Brass menuki feature family crests (家紋). Fuchi-kashira (縁頭) are plain steel with a smooth finish. The tsuba (鍔) is a mokko-gata (木瓜形) guard made of antique-finished brass.

TangGu (湯谷) Oroshigane Kobuse Blade

This blade is hand-forged (Tezukuri / 手作り) from in-house refined Oroshigane (卸し金) steel, smelted from satetsu (砂鉄) and repeatedly folded (orikaeshi-tanren / 折り返し鍛錬). Forged in Kobuse-zukuri (甲伏造) construction, this Oroshigane shares the same forging lineage as traditional Tamahagane (玉鋼), achieving comparable performance and structure while allowing the smith to refine the steel’s properties by hand.

Blade Forging Details

• Blade Name: TangGu Folded Oroshigane Kobuse Blade (甲伏造)
  

• Forging Method: This blade is forged in Kobuse-zukuri（甲伏造）style, with a hardened outer layer over a softer iron core. It is differentially hardened using clay tempering（覆土焼入れ）, producing a sharp edge, resilient spine, and a visible hamon（刃文).

• Materials: Oroshigane (卸し金) steel smelted from satetsu (砂鉄), refined in-house using traditional methods（伝統的手法による自家製鋼材）

• 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. 24 cm
• Width at Base (Motohaba 元幅): Approx. 31 mm
• Thickness at Base (Motokasane 元重): Approx. 6 mm
• Width at Tip (Sakihaba 先幅): Approx. 22 mm
• Thickness at Tip (Sakikasane先重): Approx. 4 mm
• Kissaki Length (Tip 切先長): Approx. 40 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), Ō-kissaki (Large tip 大切先)

• Forging Pattern (Hada 鍛肌): Ayasugi-hada（綾杉肌）— cedar-grain pattern with alternating waves.
• Temper Line (Hamon 刃文): Suguha（直刃刃文）— straight temper line formed by clay tempering.

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 blade has refined geometry and balanced weight, forged from Oroshigane (卸し金) steel with Kobuse (甲伏) construction—a hard outer steel layer around a softer core. Traditional folding produces an Ayasugi-hada (綾杉肌) jihada, while polishing reveals a brightened edge (Hashiro / 刃白), the patterned jihada (地肌), and a high-polish ridge line (hōmi / 峰).

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Mokko-gata（木瓜鍔）brass tsuba with aged antique finish, plain surface.
• Fuchi-Kashira (縁頭): Steel with smooth, undecorated surface.
• Menuki (目貫): Brass menuki with traditional kamon (家紋) motifs.
• Habaki (鎺): Hand-forged brass with aged antique finish.
• Samegawa (Ray Skin 柄鮫): Natural ray skin aged to a soft yellow hue.
• Handle Wrapping (Tsuka-maki 柄巻): Yellow cotton ito, tightly wrapped.

Saya and Accessories

• Saya (Scabbard 鞘): Hantai-tachi style (半太刀拵) scabbard with steel fittings at koiguchi, kurigata, and kojiri for durability.
• Saya Lacquer (鞘塗): Palm bark-style lacquer (棕櫚塗) with textured natural pattern and earthy tones.
• Sageo (Cord 下緒): Golden brown cord, tightly woven and tied.

Measurements

• Blade Weight: Approx. 0.65 kg
• Sword Weight (without Saya): Approx. 1.0 kg
• Total Weight: Approx. 1.4 kg
• Overall Length: Approx. 100 mm