Katana Dragon Abyss Sanmai Blade Unryu Koshirae 龍淵

Clay Tempered Full Tang Shinken (真剣) | Dragon Abyss Katana: TangGu (湯谷) Sanmai Blade (三枚造) + TangGu (湯谷) Unryu Koshirae (雲龍拵)

This katana is forged in sanmai（三枚）construction, with a hardened steel core between softer outer layers. The surface shows masame-hada（柾目肌）grain and a notare-komidare（のたれ交じり小乱刃文）hamon, formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）. The blade is shaped in shinogi-zukuri（鎬造）style with an iori-mune（庵棟）spine and ō-kissaki（大切先）tip. It weighs approximately 500 grams. The koshirae（拵）features a maru-gata（丸形）tsuba made of copper（銅 / Dō）with a black patina finish（煮黒 / Nuriguro）and a cloud-and-dragon motif（雲龍文様）with gold and silver details. The fuchi and kashira（縁頭）are blackened copper with matching motifs. Dragon-shaped menuki（目貫）are set under the tsuka-ito（柄糸）. The tsuka（柄）is wrapped in brown cotton ito（綿糸）using hishigami（菱紙）over aged white samegawa（本鮫皮）ray skin. The saya（鞘）is hardwood in traditional style（拵風鞘）, finished in chinkin（鎮金）lacquer with a black base and gold powder. The koiguchi（鯉口）, kojiri（小尻）, and kurigata（栗形）are reinforced with water buffalo horn（牛角）. The saya includes a kaeritsuno（返角）and slots for kozuka（小柄）and kogai（笄）. A red cotton sageo（赤色の綿下緒）is tied to the kurigata.

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: 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. 25 cm
• Width at Base (Motohaba 元幅): Approx. 30 mm
• Thickness at Base (Motokasane 元重): Approx. 5.5 mm
• Width at Tip (Sakihaba 先幅): Approx. 22 mm
• Thickness at Tip (Sakikasane先重): Approx. 3.5 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-sized tip 大切先)

• Forging Pattern (Hada 鍛肌): Masame-hada（柾目肌）— a straight grain pattern running along the blade, created through layered forging in sanmai-zukuri（三枚造）construction.
• Hamono (Blade Pattern 刃文): Notare-komidare-style hamon（のたれ交じり小乱刃文）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 blade geometry and weight distribution are shaped with a core-hardened edge in sanmai（三枚）construction. It weighs approximately 500 grams. Hand polishing shows the hakuba（刃白）edge line contrasting with the masame-hada（柾目肌）on the ji（地）surface. The shinogi ridge（鋒身筋 / Hōmi）is mirror polished.

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Maru-gata（丸形）handguard made of copper（銅 / Dō）with black patina finish（煮黒 / Nuriguro）. The surface has a cloud-and-dragon motif（雲龍文様）in high relief with gold and silver details.
• Fuchi-Kashira (縁頭): Black-patinated copper（煮黒銅）engraved with matching cloud-and-dragon motifs.
• Menuki (目貫): Dragon-shaped（龍）menuki under the tsuka-ito（柄糸）.
• Habaki (鎺): Polished copper（銅 / Dō）habaki
• Samegawa (Ray Skin 柄鮫): White ray skin（本鮫皮）under the wrap.
• Handle Wrapping (Tsuka-maki 柄巻): Brown cotton ito wrapped using hishigami（菱紙）over samegawa in a diamond pattern.

Saya and Accessories

• Saya (Scabbard 鞘): Traditional-style saya (拵風鞘), crafted from hardwood, reinforced at the koiguchi (鯉口), kojiri (小尻), and kurigata (栗形) with water buffalo horn (牛角). The front includes a kaeritsuno (返角) for sageo support and fitted slots for kozuka (小柄) and kogai (笄).
• Saya Lacquer (鞘塗): Chinkin-style (鎮金) lacquer with a black base and gold powder.
• Sageo (Cord 下緒): Red cotton sageo (赤色の綿下緒) tied to the kurigata.

Measurements

• Blade Weight: Approx. 0.5 kg
• Sword Weight (without Saya): Approx. 0.80 kg
• Total Weight: Approx. 1.2 kg
• Overall Length: Approx. 102 mm