Katana Scarlet Lion Folded Steel Blade Kōshi Koshirae 朱獅

Clay Tempered Full Tang Shinken (真剣) | Scarlet Lion Katana: TangGu (湯谷) Folded Steel Blade (折り返し鍛錬刃) + TangGu (湯谷) Kōshi Koshirae (紅獅拵)

This katana is forged in Maru-zukuri (丸造) construction from hand-forged and folded high-carbon steel (折り返し鍛錬高炭素鋼). The surface shows a refined masame-hada (柾目肌) grain, and the edge displays a graceful notare (湾刃) hamon formed through clay tempering (覆土焼入れ / Fukutsuchi Yakiire). The blade is made in shinogi-zukuri (鎬造) geometry with an iori-mune (庵棟) spine and a chū-kissaki (中切先, medium-sized tip). The koshirae (拵) features a round steel tsuba (丸形鍔) carved with a Chinese-style lion motif (唐獅子図), finished with a black patina (煮黒 / Nuriguro). The fuchi and kashira (縁頭) are also steel with black patina, carved with matching lion designs to complement the guard. The tsuka (柄) is wrapped in blue cotton ito (青色木綿柄糸) with hishigami (菱紙) over natural samegawa (本鮫皮) ray skin, forming a precise hishi-gumi (菱組) diamond pattern. The saya (鞘) is finished in red ishime-ji lacquer (赤石目塗), creating a textured stone-like surface. The koiguchi (鞘口), kojiri (鞘尻), and kurigata (栗形) are reinforced with water buffalo horn (牛角). A blue cotton sageo (青色木綿下緒) is tightly woven and tied to the kurigata, completing the elegant mounting.

TangGu (湯谷) Folded Steel Blade

This blade is hand-forged (Tezukuri / 手作り) using folded forging (折り返し鍛錬) from high-carbon steel (高炭素鋼), 

Blade Forging Details

• Blade Name: TangGu Traditionally Forged & Folded Maru Blade (丸造, 折り返し鍛錬)
• Forging Method: This blade is hand-forged and folded in the Maru-zukuri (丸造) style from high-carbon steel (折り返し鍛錬高炭素鋼). It is differentially hardened using clay tempering (覆土焼入れ), producing a hardened edge and a tougher, more resilient spine. This traditional process also results in a visible hamon (刃文).
• Materials: High-carbon steel, folded and forged using traditional methods (伝統的手法による折り返し鍛錬高炭素鋼)
• 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. 26 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. 36 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 running parallel along the blade, formed through folded forging (折り返し鍛錬) in Maru-zukuri (丸造) construction.
• Temper Line (Hamon 刃文): Notare-style hamon（のたれ刃文）formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）

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（柾目肌）with straight grain lines. A hakuba（刃白）temper line runs along the edge, formed through clay tempering（覆土焼入れ / Fukutsuchi Yakiire）. The shinogi（鋒身筋）ridge is mirror polished.

Fittings and Mountings

Blade Fittings

• Tsuba (Handguard 鍔): Maru-gata (丸形) tsuba made of steel (鋼), finished with black patina (煮黒 / Nuriguro). The surface is carved with a Chinese-style lion motif (唐獅子図).
• Fuchi-Kashira (縁頭): Steel (鋼) with black patina (煮黒 / Nuriguro), carved with matching lion designs, paired with the tsuba.
• Menuki (目貫): Set of menuki placed beneath the blue tsuka-ito (柄糸).
• Habaki (鎺): Shakudō（赤銅 / purple copper）habaki, polished.
• Samegawa (Ray Skin 柄鮫): Natural unbleached ray skin（本鮫皮）under the wrap.
• Handle Wrapping (Tsuka-maki 柄巻): Blue cotton ito wrapped with hishigami (菱紙) in 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): Red ishime-ji lacquer (赤石目塗) with a textured, matte finish.
• Sageo (Cord 下緒): Blue cotton sageo, tied in traditional style.

Measurements

• Blade Weight: Approx. 0.7 kg
• Sword Weight (without Saya): Approx. 1.0 kg
• Total Weight: Approx. 1.2 kg
• Overall Length: Approx. 103 mm