Katana Earthen Sakura Oroshigane Kobuse Blade Tsuchizakura Koshirae 土桜

Folded Oroshigane Steel Shinken (真剣) | Earthen Sakura Katana: TangGu (湯谷) Oroshigane (卸し金) Kobuse Blade (甲伏造) + TangGu (湯谷) Tsuchizakura Koshirae（土桜拵）

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 layer encasing 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 traditional clay tempering (覆土焼入れ). The blade is shaped with an imposing Ō-kissaki (大切先), enhancing both visual presence and cutting authority. The saya (鞘) is finished in Kasshoku Nashiji lacquer (褐色梨地塗り), presenting a warm, earthy tone with a refined, softly shimmering granular texture. The koiguchi, kurigata, and kojiri are reinforced with water buffalo horn for durability and long-term structural integrity. The tsuka (柄) features genuine black samegawa (黒鮫皮), paired with deep brown tsuka-ito (濃茶柄糸), tightly wrapped over hishigami (菱紙) to produce clean, well-defined diamond patterns (菱組) and a secure grip. The menuki (目貫) are crafted from hakudō (白銅), shaped in refined sakura motifs (桜図), subtly integrated into the overall aesthetic. The fuchi and kashira (縁頭) are also made of hakudō (白銅), finished in a darkened patina (煮黒), and decorated with Higo-style sakura motifs over an Ishime-ji ground (肥後石目地桜図). The tsuba (鍔) is a hand-finished Ishime-ji iron guard (石目地鉄鍔), presenting a subdued, stone-textured surface that complements the overall understated design. Completing the mounting, the habaki (鎺) is crafted from brass (真鍮), featuring a traditional Nekogaki (猫掻) texture, complemented by a contrasting polished surface.

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 71 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. 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): 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 Ishime-ji iron tsuba (石目地鉄鍔), featuring a subtly textured, stone-like surface with a subdued blackened finish.
• Fuchi-Kashira (縁頭): Made from hakudō (白銅), finished in a darkened patina (煮黒), and decorated with Higo-style sakura motifs (肥後桜図) over an Ishime-ji ground.
• Menuki (目貫): Crafted from hakudō (白銅), shaped in refined sakura motifs (桜図)
• Habaki (鎺): A brass habaki with a traditional Nekogaki (猫掻) texture, complemented by a contrasting polished surface.
• Samegawa (Ray Skin 柄鮫): Genuine black rayskin (黒鮫皮)
• Handle Wrapping (柄巻): Deep brown silk (or cotton) tsuka-ito (濃茶柄糸), tightly wrapped over hishigami (菱紙) to form clean, 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): Finished in Kasshoku Nashiji lacquer (褐色梨地塗り), featuring a warm brown tone with a fine, subtly shimmering granular texture.
• 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