The Rai school was said to be founded by a smith named Kuniyoshi, who was believed to have come from Korea. Rai in kanji means " Come", but the son, Kuniyuki is always regarded as the founder of the Rai school.
This is a 750 year old tachi, Middle of Kamakura period (Kougen era/circa 1256) Yamashiro
Length of cutting edge 73.6cm Curvature 2.2cm Width of base 29.1mm Width of Yokote 20.5mm Thickness of base 7.0mm
Sugata(configuration) : Shinogi-zukuri, Iori-mune. Osuriage substantially shortened with a highly defined curve. It has an Ikubi-style Chu-kissaki and the Kitae(forging pattern) is Ko-Itame (fine wooden grain), mixing with large Itame-hada wares. Sparkling hard metal granules of Ji-nie appears that gives off diffused reflection with mottled effect so called "Rai-Utsuri".
Hamon(tempering pattern) : Hamon is Ko-nie a bit on stronger side Nie based, wide undulating Notare line with delicate small Gunome, small clove outline of Choji. Deep sparkling Nie accumulates on boundary line where long or short Nie lines of Kinsen and Sunagashi and slanting downward Kyo-saka-ashi appears.
The interior of hamon is filled with limpid Nioi that comes from abundant activities of forging and quenching using carefully selected different element of fine steel.
Boshi (tip): Boshi forms minutely irregular small circle turns back shortly.
Nakago(tang) : The tang is substantially shortened O-suriage. Two Mekugi-ana retaining holes. Slightly leftward file marks Katte-sagari.The heel shape is shallow Kurijiri double-bevelled.
Although Nakago was substantially shortened to be an O-suriage, it holds a highly defined curve like an arch, generous curved - unrestricted shape with a medium Kissaki so called Ikubi-style with a clear characteristic of mid-Kamakura period sword.
The forging of this blade comes from carefully selected fine steel under Yamashiro Rai-school tradition generates Rai-Utsuri mottled reflection like a mist hung over the forest.
Hamon of founder KUNIYUKI is rather flamboyant small Choji-midare like this example unlike in the works of later generations of Rai-school. Boundary line is vividly clear in a bit on strong side of Ko-Nie and luminous Ji-nie with mottled effect Rai-Utsuri covers vividly on Hiraji.
Superb polish by Ono Kokei who wrote the Sayagaki mentions that this katana was elaborately polished in 1989 by a living national treasure Ono Kokei (1913-94).
The said blade has a gold foiled double layer Habaki collar and housed in a Shirasaya. (Sayagaki written by Ono Kokei)
reference : Honma Junji/Sato Kan'ichi, Nihonto Taikan, Otsuka Kogei-sha, 1968
This sword came with Hozon paper and I resubmitted it to Tokubetsu Hozon and now, it is going to try for Juyo paper.
This sword is mounted in shirasaya and has an edo period same strip koshirae with saya leather protector with family mon imprinted.