Katana of the Echizen Rai school from the 14th century with CERTIFICATE

Katana of the Echizen Rai school from the 14th century with CERTIFICATE
This katana is an artifact crafted by a representative of the Yamashiro school, the most prominent of the five schools that make up the Gokaden.
The Echizen Rai school was founded by Rai Kuniyasu (来国安), who moved from Yamashiro to Echizen around the mid-14th century to establish a branch of the Rai school. Blades from the Echizen Rai school and the Rai school share similar characteristics, as is the case with this blade, which is in the style of the famous Rai Kunitoshi (来國俊).
The steel is, of course, tamahagane. The blade’s appearance and layering are Orikaeshi Sanmai. The soft core is covered with medium-hard steel scales, and the cutting edge itself is tempered to a hardness unique to each school.
What makes this sword unique, besides its maker, is the double Bo-Hi, or soe-Hi. Swords crafted in periods prior to the Edo period were made for strenuous combat. The use of this type of Bo-Hi made the sword more balanced, more stable during cutting (reducing blade vibration), and made the blade stronger, making it less susceptible to deformation during “intensive use.”
The NBTHK Hozon certificate dated March 4, 2022, confirms the work was done by the blacksmith Echizen-Rai [越前来]. The precise designation of the Echizen-Rai school narrows the dating to the “Northern and Southern Court” period of Nanbokucho [1336-1392]. Certification under the new rules is now very rigorous, and only pieces distinguished by artistic merit and craftsmanship can receive it.
Total length: 79.1 cm
Length of the “Nagasa” cutting edge: 63.7 cm. Sori curvature: 1.4 cm.
Width at the “Moto-haba” habaki: 2.8 cm.
Width at the “Saki-haba” yokote: 2.4 cm.
Blade thickness at the “Moto-gasane” habaki: 0.65 cm.
Blade thickness at the “Saki-gasane” yokote: 0.55 cm.

Chu-Suguha-type hamon, distinct and aesthetic.

Chu-Kissaki-type kissaki.

Nakago ubu [the sword was not shortened] finished in the Yamashiro Jiri style, no signature [mumei].
Habaki made of brass.