Katana Dragon Current Sanmai Blade Seiryū Koshirae 龍瀞

Clay Tempered Full Tang Shinken (真剣) | Dragon Current Katana: TangGu (湯谷) Sanmai Blade (三枚造) + TangGu (湯谷) Seiryū Koshirae (青龍拵)

This katana, named Dragon Current, embodies the tranquil strength and flowing grace of the mythical azure dragon. The blade is forged in Sanmai (三枚構造) construction, combining a hardened steel core with softer outer layers to balance sharpness and resilience. The surface reveals Masame-hada (柾目肌) — fine straight grain lines symbolizing steadfast discipline — while the Notare hamon (湾刃) undulates gently like ripples across still water. Fitted in Seiryū Koshirae (青龍拵), the fittings are crafted from silver-bronze patinated in black (白銅煮黑) and intricately carved with wave-and-dragon reliefs, symbolizing wisdom and power in harmony. The saya (鞘) is finished in an elegant Uchigane-nuri (烏金塗) lacquer, where deep black mingles with warm copper tones, resembling the hidden glow of molten fire beneath the sea’s surface.
A dark navy tsuka-ito complements the theme of calm authority, paired with a chocolate-brown sageo, bringing visual balance to this refined ensemble.

TangGu (湯谷) Sanmai Blade

This blade is hand-forged (Tezukuri / 手作り) using our own refined steel in Sanmai-zukuri（三枚造）construction, with a hard edge forge-welded between two softer outer layers.

Blade Forging Details

• Blade Name: TangGu Traditionally Forged Sanmai Blade (三枚造)
• Forging Method: This blade is forged in the Sanmai-zukuri（三枚造）style, with a hard steel core forge-welded between two layers of softer outer steel. It is differentially hardened using clay tempering（覆土焼入れ）, producing a hardened edge and a softer spine. This process also creates a visible hamon（刃文）
• Materials: Steel 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 73 cm
• Tang Length (Nakago 茎長): Approx. 24 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. 35 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): The blade shows masame-hada（柾目肌）with long, straight grain lines. Variations in the grain include itame-hada（板目肌）and transitional textures, created through layered forging in the sanmai-zukuri（三枚構造）style.
• Temper Line (Hamon 刃文): The blade shows a Notare-style hamon（のたれ刃文）formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）. The hamon runs along the edge with masame-hada（柾目肌）beneath.

Special Features and Workmanship

Hi (Groove) Engraving

• Type: Marudome-Hi (丸止樋), deeply engraved
• Processing Range: Extends to the tip, fully polished inside the groove

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 shows masame-hada（柾目肌）with straight grain lines. Along the edge is a hakuba（刃白）pattern. The shinogi-ji and hōmi ridge（峰）are polished and defined.

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Maru-gata tsuba（丸形）, crafted from white copper（白銅）with blackened patina（煮黒仕上げ / Nibu-iro). The surface shows clouds, dragons, waves, and rocks（雲・龍・波・岩）.
• Fuchi-Kashira (縁頭): Blackened white copper（煮黒仕上げの白銅）with engraved wave-dragon motif（波龍図案）on both fuchi（縁）and kashira（頭）.
• Menuki (目貫): Blackened white copper（煮黒白銅）menuki shaped as sword-dragons（剣龍）, placed under the tsuka wrap.
• Habaki (鎺): Smoothly polished white copper (白銅 / Hakudō) habaki
• Samegawa (Ray Skin 柄鮫): Hon-samegawa（本鮫皮 / genuine ray skin）with kofū shiage（古風仕上げ / antique finish).
• Handle Wrapping (Tsuka-maki 柄巻): Dark navy cotton ito (木綿糸) in hineri-maki (捻巻) style with hishigami (菱紙), forming precise diamond patterns along the tsuka.
  

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): The saya is finished in urushi-style black lacquer with reddish-brown mottling（烏金塗 / U-gin Nuri）.
• Sageo (Cord 下緒): Chocolate-brown cotton sageo tied in a traditional style.

Measurements

• Blade Weight: Approx. 0.6 kg
• Sword Weight (without Saya): Approx. 0.95 kg
• Total Weight: Approx. 1.2 kg
• Overall Length: Approx. 102 mm