Katana Vermilion Bolt Maru Blade Kōden Koshirae 赤雷

Shinken (真剣) | Vermilion Bolt Katana: TangGu (湯谷) Maru Blade (丸造) + TangGu (湯谷) Kōden Koshirae (紅電拵)

This katana is forged in a Maru construction with high-performance modern steel. The blade features a decorative suguha-style hamon (直刃風刃文), polished to show the temper line. The tsuba is a Musashi-gata sukashi tsuba (武蔵形透鍔), forged from tetsu (鉄地, iron) with a blackened finish (yaki-sabi 煮黒). Its double-ring sukashi (透かし) design provides lightness and strength. The fuchi-kashira (縁頭) are made from shiragane (白銅, white copper), polished (migaki 磨き) without engravings. The habaki (鎺) is made from shakudo (赤銅), polished for transition between blade and fittings. The menuki (目貫), with a sword-and-dragon motif (剣龍図目貫), are made from shiragane (白銅), blackened and polished. The tsuka is wrapped in black silk ito (黒色柄糸) over natural samegawa (鮫皮, ray skin), with hishigami (菱紙) forming a diamond pattern (hishi-gumi 菱組). The saya is finished in aka-urushi (赤漆). The koiguchi (鞘口), kurigata (栗形), and kojiri (鐺) are reinforced with water buffalo horn (gyūkaku 牛角). The black silk sageo (黒色下緒) completes the mounting.

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): Decorative suguha-style (直刃風) hamon (Fully quenched blade; not differentially hardened)

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:
  • 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): Musashi-gata (武蔵形) Sukashi Tsuba – Forged from tetsu (鉄地, iron), blackened (yaki-sabi 煮黒), with a double-ring sukashi (透かし) design.
• Fuchi-Kashira (縁頭): Hakudo (白銅, white copper), polished (migaki 磨き), no patterns.
• Menuki (目貫): Sword-and-dragon motif (剣龍図目貫), hakudo (白銅), blackened and polished.
• Habaki (鎺): Shakudo (赤銅) Habaki – Forged from shakudo (赤銅), polished surface (migaki 磨き).
• Samegawa (Ray Skin 柄鮫): Natural samegawa (鮫皮), under tsuka-maki.
• Handle Wrapping (Tsuka-maki 柄巻): Black silk ito (黒色正絹柄糸), wrapped with hishigami (菱紙) in hishi-gumi (菱組) pattern.

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): Aka-urushi (赤漆) with a glossy, reflective finish.

• Sageo (Cord 下緒): Black silk sageo (黒色下緒), 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