Katana Moon Rabbit Sanmai Blade Isei Koshirae 赤宵

Clay Tempered Full Tang Shinken (真剣) | Moon Rabbit Katana: TangGu (湯谷) Sanmai Blade (三枚造) + TangGu (湯谷) Isei Koshirae (威静拵)

This katana is mounted in the Isei Koshirae（威静拵）. The blade is forged in Sanmai（三枚構造）construction, with a hardened core steel enclosed by softer outer layers. It is clay tempered（覆土焼入れ / Fukutsuchi Yakiire）, forming a Notare-style hamon（のたれ刃文）along the edge. The saya（鞘）is finished in red lacquer with sparkling highlights. The koiguchi（鞘口）, kurigata（栗形）, and kojiri（鞘尻）are reinforced with buffalo horn（牛角）. A brown cotton sageo（下緒）is tied in a traditional style. The tsuka（柄）is wrapped in brown cotton ito using hishigami（菱紙）over white samegawa（本鮫皮）in a diamond pattern. The menuki（目貫）are geometric designs in white copper（白銅）. The fuchi-kashira（縁頭）are brass（真鍮）with black patina（煮黒仕上げ）and carved decoration. The tsuba（鍔）is a round maru-gata（丸形）guard made of brass（真鍮）with blackened boiled finish（煮黒仕上げ）and carved with a tiger and rabbit motif（虎兔図）.

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. 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): Masame-hada（柾目肌）— a straight-grained forging pattern created through layered forging in the sanmai-zukuri（三枚造）style.
• Hamono (Blade Pattern 刃文): Notare-style hamon（のたれ刃文）formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）, running along the edge.

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 has defined geometry and weight distribution with a core-hard edge from the sanmai（三枚）construction. The polish shows the edge (hakuba 刃白), matte ji (jihada 地肌), and polished shinogi line (hōmi 峰).

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Maru-gata（丸形）tsuba made of brass（真鍮）with a carved tiger and rabbit motif（虎兔図）and finished with black patina（煮黒仕上げ）.
• Fuchi-Kashira (縁頭): Brass（真鍮）with black patina（煮黒仕上げ）, engraved.
• Menuki (目貫): Geometric-style menuki made of polished white copper（白銅）, placed under the tsuka-ito（柄糸）.
• Habaki (鎺): Red copper（赤銅 / Akagane）habaki with a smooth finish.
• Samegawa (Ray Skin 柄鮫): Natural ray skin（本鮫皮）under the wrap.
• Handle Wrapping (Tsuka-maki 柄巻): Brown cotton ito wrapped using hishigami（菱紙）in a diamond pattern.

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): Finished in red lacquer with sparkling highlights.
• Sageo (Cord 下緒): 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