Katana Vajra Maru Blade Kongo Koshirae 大椿

Shinken (真剣) | Vajra Katana: TangGu (湯谷) Maru Blade (丸造) + TangGu (湯谷) Kongo Koshirae (金剛拵)

This koshirae combines practical construction with a traditional aesthetic. The saya is finished in black lacquer with a speckled shimmer. The koiguchi, kurigata, and kojiri are reinforced with water buffalo horn. A black cotton sageo is tied in a standard pattern. The tsuka has a black silk ito wrap over natural white samegawa (ray skin), with hishigami (paper inserts) used for consistent diamond shaping. The menuki are white copper fittings shaped as double-headed Vajra (金剛杵). The fuchi and kashira are blackened copper with raised Vajra motifs. The tsuba is a mokko-style guard (木瓜鍔) made of blackened iron, with a solid four-lobed form and no decorative cutouts.

TangGu (湯谷) Maru Blade

This blade is hand-forged (Tezukuri / 手作り) using high-performance modern steel (現代鋼), with a monosteel construction known as 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 style, using a single piece of modern high-performance steel, and fully heat-treated (全体焼入れ) throughout the entire blade for uniform hardness and durability.
• Materials: Modern high-performance steel (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): None (Fully quenched blade; not differentially hardened)

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-rough polish 上・下研ぎ
• High-reflection mirror finish 上・鏡面仕上げ研磨
• Key Features:
• Refined blade geometry and balanced weight distribution
• Exceptional sharpness, durability, and a clean, modern mirror-polished surface

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Mokko-style Tsuba (木瓜鍔) – Blackened Iron (鉄地), featuring a solid four-lobed silhouette with no openwork. A minimalist and practical guard, emphasizing structural simplicity.
• Fuchi-Kashira (縁頭): Decorated with double Vajra (金剛杵) motifs, crafted from blackened and polished white copper, symbolizing spiritual strength and protection.
• Menuki (目貫): Double Vajra (金剛杵) motif menuki crafted from polished white copper, symbolizing protection, strength, and spiritual discipline.
• Habaki (鎺): Crafted from white copper (shiragane / 白銅) with a smooth – finish.
• Samegawa (Ray Skin 柄鮫): Premium natural ray skin
• Handle Wrapping (Tsuka-maki 柄巻): High-quality black silk ito, wrapped with hishigami (paper triangles)

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Saya and Accessories

• Saya (Scabbard 鞘): Traditional-style design reinforced with water buffalo horn at the koiguchi (mouth), kojiri (end), and kurigata (cord knob).
• Saya Lacquer (鞘塗): Glossy black lacquer with subtle speckled shimmer effect.
• Sageo (Cord 下緒): High-quality black silk sageo for a secure and characterful presentation

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