Katana Mitsuba Aoi Radiance Kobuse Blade Kin-aoi Koshirae 葵耀

Clay Tempered Full Tang Shinken (真剣) | Mitsuba Aoi Radiance Katana: TangGu (湯谷) Kobuse Blade (甲伏造) + TangGu (湯谷) Kin-aoi Koshirae (金葵拵)

This uchigatana is named Mitsuba Aoi Radiance, mounted in the Kin-aoi Koshirae, a design with Tokugawa（徳川）symbolism. The tsuba（鍔）is a maru-gata（丸形 / round-shaped）form, crafted from gilded brass and finished with nanako-ji（魚子地 / fish-roe texture). Mitsuba Aoi（徳川三葉葵）crests are carved in relief across the surface. The fuchi and kashira（縁頭）continue this motif, also made of gilded brass with nanako finish and the same crests. Beneath the handle wrapping, the menuki（目貫）depict the Mitsuba Aoi emblem. The blade is forged in Kobuse-zukuri（甲伏造）construction, with a hardened outer jacket around a softer core. The surface shows masame-hada and mokume-hada（柾目肌交杢目肌）created through orikaeshi-tanren（折返し鍛錬）folding. A gunome-midare hamon（互の目乱れ刃文）runs along the edge, formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）. The tsuka（柄）is wrapped in golden-yellow cotton ito（黄色の木綿糸）in hineri-maki（捻巻）style, with hishigami（菱紙）inserting a diamond pattern. Underneath lies hon-samegawa（本鮫皮 / genuine ray skin）with kofū shiage（古風仕上げ / antique finish）. The saya（鞘）is finished in kin-nashiji（金梨子地塗 / gold-speckled lacquer）with metallic flakes in the surface. Buffalo horn（牛角 / Gyu-kaku）is used for reinforcement at the koiguchi（口金）, kurigata（栗形）, and kojiri（鞘尻）. A golden-yellow sageo（下緒）is tied at the kurigata.

TangGu (湯谷) Kobuse Blade

This blade is hand-forged (Tezukuri / 手作り) using our own refined steel, following the principles of Japanese swordsmithing. It features a Kobuse-zukuri (甲伏造) laminated construction, reflecting the structure of traditional Tamahagane (玉钢) swords.

Blade Forging Details

• Blade Name: TangGu Traditionally Forged Kobuse Blade (甲伏造)
  

• Forging Method: This blade is forged in the Kobuse-zukuri（甲伏造） style, where a hardened outer layer of steel is forge-welded over a softer inner core. It is differentially hardened using traditional clay tempering（覆土焼入れ）, resulting in a sharp edge, resilient spine, and a visible hamon（刃文） that reflects both performance and craftsmanship.

• 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. 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 forging pattern shows Masame-hada with Mokume influence（柾目肌交杢目肌）, where masame-hada（柾目肌） fine straight grain lines run longitudinally along the blade, and mokume-hada（杢目肌） swirling woodgrain-like patterns appear in layers. This is achieved through folding and directional forging in the orikaeshi-tanren（折返し鍛錬） process.
• Hamono (Blade Pattern 刃文): The blade has a Gunome-midare（互の目乱れ刃文） temper line, with alternating rounded peaks and valleys formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）. Clay is applied to specific areas of the blade before quenching to control the hardness gradient and produce this pattern.

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 surface shows Masame-hada and Mokume-hada（柾目肌交杢目肌）, combining straight grain lines and swirling woodgrain patterns. A Gunome-midare hamon（互の目乱れ刃文） with alternating peaks and curves is formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）. The ridge line (Hōmi 峰) is defined through traditional polishing.

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Maru-gata tsuba（丸形鍔）, crafted from gilded brass（黄銅鍍金） with a nanako-ji（魚子地） surface texture. Decorated with Mitsuba Aoi（徳川三葉葵） crests carved in relief.
• Fuchi-Kashira (縁頭): Made of gilded brass（黄銅鍍金） with nanako-ji（魚子地） background. Engraved with Mitsuba Aoi crests（三葉葵紋） matching the tsuba in motif and finish.
• Menuki (目貫): Gilded brass Mitsuba Aoi crests（三葉葵紋）, placed under the tsuka-maki（柄巻）.
• Habaki (鎺): Forged from polished copper（磨き銅 / Migaki-dō） with rounded edges.
• Samegawa (Ray Skin 柄鮫): Wrapped in hon-samegawa（本鮫皮） with antique finish（古風仕上げ / Kofū shiage）.
• Handle Wrapping (Tsuka-maki 柄巻): Golden-yellow cotton ito（黄色の木綿糸 / Kiiro no momen ito） in hineri-maki（捻巻） style with hishigami（菱紙） for structure.

Saya and Accessories

• Saya (Scabbard 鞘): The saya（鞘）is made in uchigatana koshirae style（打刀拵）with buffalo horn（牛角 / Gyu-kaku）reinforcements at the koiguchi（口金）, kurigata（栗形）, and kojiri（鞘尻）.
• Saya Lacquer (鞘塗):  Finished in kin-nashiji（金梨子地塗）, a speckled gold lacquer technique with metallic particles in the coating.
• Sageo (Cord 下緒): Golden-yellow cotton sageo（黄色の木綿下緒 / Kiiro no momen sageo）tied at the kurigata（栗形）.

Measurements

• Blade Weight: Approx. 0.65 kg
• Sword Weight (without Saya): Approx. 1.00 kg
• Total Weight: Approx. 1.25 kg
• Overall Length: Approx. 102 mm