Katana Crane’s Wave Maru Blade Kuronami Koshirae 黒浪

Clay Tempered Full Tang Shinken (真剣) | Crane’s Wave Katana: TangGu (湯谷) Maru Blade (丸造) + TangGu (湯谷) Kuronami Koshirae (黒浪拵)

This katana is hand-forged (Tezukuri / 手作り) from high-carbon modern steel (高炭素現代鋼) in the Maru-zukuri (丸造) style. The blade is clay-tempered (yaki-ire / 焼入れ) to produce a gonome hamon (互の目刃文). The koshirae includes a maru-gata tsuba (丸形鍔) made of tetsu (鉄地, iron) with a blackened finish (煮黒) and an openwork crane motif (透かし鶴). The fuchi-kashira (縁頭) are made of hakudo (白銅), blackened (煮黒), and engraved with wave motifs (波紋). The habaki (鎺) is made of suaka (素赤銅), and the menuki (目貫) are made of hakudo (白銅), blackened (煮黒), and shaped in a wave design (波模様). The tsuka is wrapped in brown cotton ito (茶色木綿柄糸) over natural samegawa (鮫皮) with hishigami (菱紙) forming a diamond pattern (菱組). The saya is finished in black ishime-ji lacquer (黒石目塗) with a textured surface. The sageo (下緒) is brown cotton (茶色木綿下緒), tightly woven.

TangGu (湯谷) Maru Blade

This blade is hand-forged (Tezukuri / 手作り) from high-carbon modern steel (高炭素現代鋼) in a monosteel construction called Maru-zukuri (丸造).

Blade Forging Details

• Blade Name: TangGu Traditionally Forged Maru Blade (丸造)
• Forging Method: This blade is forged in the Maru-zukuri (丸造) style from a single piece of modern high-carbon steel. It is clay-tempered (yaki-ire / 焼入れ) to produce a hardened edge with a visible hamon (刃文).
• Materials: Modern high-carbon steel (kōtanso gendai-kō / 高炭素現代鋼)
• Purpose: Designed for Iaido (non-sharpened), Kenjutsu, and Tameshigiri (test cutting) practice

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): None (Modern monosteel; no visible hada)
• Hamono (Blade Pattern 刃文): Clay-tempered gonome-style (互の目) hamon – The blade is differentially hardened (yaki-ire / 焼入れ) to produce a temper line.

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:
  • High-grade shaping polish 上・成形研磨
  • High-grade rough polish 上・下研ぎ
  • High-grade final polish 上・仕上げ研磨
• Key Features:
  • Refined blade geometry and balanced weight distribution
  • Exceptional sharpness and durability with a clean, bright-polished edge (Hashiro)
    

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Maru-gata Tsuba (丸形鍔) – Forged from tetsu (鉄地, iron) with an openwork crane motif (透かし鶴).
• Fuchi-Kashira (縁頭): Made from hakudo (白銅, white copper), blackened (煮黒) and engraved with wave motifs (波紋).
• Menuki (目貫): Made from hakudo (白銅), blackened (煮黒) and shaped in a wave design (波模様).
• Habaki (鎺): Shakudo Habaki (赤銅鎺) – Made from reddish copper alloy (shakudo / 赤銅) with a polished surface.
• Samegawa (Ray Skin 柄鮫): Natural rayskin (samegawa / 鮫皮) beneath the tsuka-maki.
• Handle Wrapping (Tsuka-maki 柄巻): Brown cotton ito wrapped over hishigami (菱紙) in a diamond pattern (菱組).

Saya and Accessories

• Saya (Scabbard 鞘): Traditional-style saya (拵風鞘), reinforced with water buffalo horn (牛角) at the koiguchi (鞘口), kojiri (鐺), and kurigata (栗形) for added durability.
• Saya Lacquer (鞘塗): Black ishime-ji lacquer (黒石目塗) with a textured finish.
• Sageo (Cord 下緒): Brown cotton sageo (茶色木綿下緒), tightly woven.

Measurements

• Blade Weight: Approx. 0.65 kg
• Sword Weight (without Saya): Approx. 1.0 kg
• Total Weight: Approx. 1.3 kg
• Overall Length: Approx. 102 mm