Antique Japanese Tantō, Mumei, Attributed to Uda Kunihisa (宇多国久) by the NBTHK, and to Rai Hidetsugu (来秀次) by Kazuo Tokunō — Two Scholarly Attributions on a Single Blade

A slender, serene hoso-suguha in the spirit of Yamato-den, over a tightly kneaded itame-hada with visible chikei and yubashiri, preserved in museum-grade condition

We are pleased to present an extraordinary Kōtō-period tantō of museum-grade preservation, carrying two distinct, high-level scholarly attributions from renowned appraisal authorities. Offered in flawless condition, the blade showcases a slender, serene suguha that echoes the pristine beauty of classical Yamato tradition, backed by official NBTHK Hozon Tōken certification alongside a historic paper by master researcher Kazuo Tokunō.

On two major attributions — Rai Hidetsugu vs. Uda Kunihisa

This piece is uniquely fascinating due to two distinct, highly respected appraisals.

Rai Hidetsugu (来秀次) — October 2000 appraisal: Authenticated with an appraisal paper by Kazuo Tokunō (founder of the United Association of Japanese Sword Research), who attributed the blade to Rai Hidetsugu, active during the Jōji era of the Nanboku-chō period. Said to be the son of Kunihide (a pupil of the 1st-generation Rai Kunitsugu), Hidetsugu is an enigmatic master whose surviving works are exceptionally rare.

Uda Kunihisa (宇多国久) — NBTHK Hozon certificate (August 2025): Officially certified as Hozon Tōken by the NBTHK, attributing the work to Kunihisa of the Uda school (son of Kunifusa). Originating from Uda in Yamato Province before relocating to Etchū Province in the late Kamakura period, the Uda school was famed for combining Yamato steel texture with formidable cutting capability.

Workmanship and condition

Considering its substantial age, the blade remains in exceptionally superb preservation, entirely free of flaws, chips, or rust. Polished to perfection, the jigane is a tightly kneaded itame-hada (wood-grain pattern) enriched with visible chikei (dark lines within the steel) and yubashiri (spilling nie). The hamon is a refined, slender hoso-suguha (thin straight temper line) crafted in the spirit of Yamato-den — a design engineered for ultimate practical efficiency yet achieving breathtaking aesthetic purity. The bōshi (tip temper) enters straight (massugu) and turns back sharply (togatte kaeru).

Form

A beautifully proportioned hira-zukuri tantō with a subtle, elegant uchizori (inward curvature). Measuring 24.4 cm in edge length, with a thickness of 5.7 mm and a motohaba of 25.2 mm, it offers a light (140 g) yet well-balanced in-hand presence, embodying the timeless grace of classic Kōtō daggers.

The mounting (shirasaya)

The blade is safely housed in a traditional shirasaya (plain wood resting scabbard), ensuring the pristine state of its polished steel and refined line is preserved for generations to come.

Certification and dual documentation

NBTHK Hozon Tōken (保存刀剣): issued August 2025, certifying the blade as an authentic, high-value Kōtō work by Uda Kunihisa. Kazuo Tokunō appraisal certificate: issued October 2000, attributing the blade to the Nanboku-chō master Rai Hidetsugu.

Boasting flawless, museum-grade health, a classic Kōtō aura, and a captivating history supported by both NBTHK certification and Kazuo Tokunō's appraisal, this unsigned ubu tantō is a rare jewel worthy of a centerpiece in any distinguished Japanese sword collection.

Specifications

• Type: Tantō (短刀), hira-zukuri with iori-mune; ubu, mumei (unsigned); Kōtō period
• Smith: Attributed to Uda Kunihisa (宇多国久) by the NBTHK / to Rai Hidetsugu (来秀次) by Kazuo Tokunō
• Signature (mei): Unsigned (mumei), ubu nakago
• Jigane: Well-kneaded itame-hada with visible chikei and yubashiri
• Hamon: Slender, serene hoso-suguha (Yamato style)
  
• Length of edge (nagasa): 24.4 cm (approx. 9.61 in / approx. 8 sun 1 bu)
• Curvature (sori): Uchizori (inward curve)
• Width at base (motohaba): 25.2 mm (approx. 0.99 in)
• Thickness at base (motokasane): 5.7 mm (approx. 0.22 in)
• Peg holes (mekugi-ana): 1
• Weight (blade only): 140 g
• Condition: Exceptional, museum grade; flawless, no rust or chips
• Mounting: Shirasaya
• Certification: NBTHK Hozon Tōken (Uda Kunihisa); Kazuo Tokunō appraisal certificate (Rai Hidetsugu)
• Registration No.: Tokyo No. 284454 (東京 第284454号)