Katana Silent Raden Oroshigane Kobuse Blade Seizan Koshirae 静山

Folded Oroshigane Steel Shinken (真剣) | Silent Raden Katana: TangGu (湯谷) Oroshigane (卸し金) Kobuse Blade (甲伏造) + TangGu (湯谷) Seizan Koshirae（静山拵）

This katana brings together the refinement of traditional craftsmanship and the structural integrity required for practical use. The blade is forged from in-house refined Oroshigane (卸し金) steel in Kobuse-zukuri (甲伏造) construction, featuring a resilient outer jacket wrapped around a softer core—an approach rooted in classical sword-making to achieve both durability and shock resistance. Folding produces a mixed mokume-hada and masame-hada grain pattern (杢目肌・柾目肌交じり), while polishing reveals a natural and flowing Gonome-Midare hamon (互目乱刃文) formed through clay tempering (覆土焼入れ). The saya (鞘) is finished in Raden Fuemaki lacquer (螺鈿笛巻塗り鞘), incorporating inlaid raden elements that produce a subtle, shifting iridescence under light. The koiguchi, kojiri, and kurigata are reinforced with water buffalo horn. The tsuka (柄) features a deep brown tsuka-ito (濃茶柄糸) tightly wrapped over natural white samegawa (白鮫皮), with hishigami (菱紙) used throughout for enhanced tightness and clean, well-defined diamond shaping (菱組). The menuki (目貫) are crafted from hakudō (白銅), shaped in a stylised ken (剣) motif, subtly integrated into the overall design. The fuchi and kashira (縁頭) are also made of hakudō (白銅), finished in a darkened patina (煮黒), and adorned with raised vajra (金剛杵) motifs. The tsuba (鍔) is a hand-finished Musashi Sukashi iron guard (武蔵透かし鉄鍔) with sekigane (責金), presenting a restrained openwork design in a subdued blackened finish. The habaki (鎺) is crafted from white copper (白銅), featuring a traditional Nekogaki (cat-scratch / 猫掻) finish.

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: Suitable for Kenjutsu and Tameshigiri (test cutting) practice, collection, and display. Unsharpened blades are available for Iaido upon request.

Blade Specifications

• Blade Length (Nagasa刃長): Approx 72 cm
• Handle Length (Tsuka 柄長): Approx. 25 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. 37 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): Mokume-hada mixed with Masame-hada（杢目肌・柾目肌交じり）— a composite pattern showing wood-grain swirls with straight grain elements, created through repeated folding and layering.
• Temper Line (Hamon 刃文): Gonome-Midare (互目乱刃) — a flowing, irregular temper line characterized by alternating rounded peaks, created through traditional clay tempering (覆土焼入れ).

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 

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Hand-finished Musashi Sukashi iron tsuba (武蔵透かし鉄鍔) with sekigane (責金)
• Fuchi-Kashira (縁頭): Made from hakudō (白銅), finished in a darkened patina (煮黒), featuring raised vajra (金剛杵) motifs.
• Menuki (目貫): Crafted from hakudō (白銅), shaped in a stylised ken (sword / 剣) motif
• Habaki (鎺): A white-copper habaki engraved in the traditional Nekogaki (Cat-scratch / 猫掻) pattern.
• Samegawa (Ray Skin 柄鮫): Natural white rayskin (白鮫皮)
• Handle Wrapping (柄巻): Deep brown silk (or cotton) ito (濃茶柄糸), tightly wrapped over hishigami (菱紙) to form precise, uniform diamond patterns (菱組).

Saya and Accessories

• Saya (Scabbard 鞘): Traditional-style design reinforced with water buffalo horn at the koiguchi (mouth), kojiri (end), and kurigata (cord knob).
• Saya Lacquer (鞘塗): Raden Fuemaki lacquer (螺鈿笛巻塗り鞘) – Featuring inlaid raden (螺鈿) elements integrated into a refined lacquered surface
• Sageo (Cord 下緒): Japanese-made sageo available in multiple colors

Measurements

• Blade Weight: Approx. 0.65 kg
• Sword Weight (without Saya): Approx. 1.0 kg
• Total Weight: Approx. 1.35 kg
• Overall Length: Approx. 101 mm