Previous answer is
　 Mumei (Ko Mihara)
無銘（古三原）

Special feature: Bingo mihara school is a group of sword makers that prospered
from the end of the Kamakura period to the end of the Muromachi
period. The Mihara school has a strong Yamato temperament,
but it is said that there were many villas and shrines in the country
and there were many exchanges with the central Kinai area. The style
is that Shirake Utsuri appears on Mokume hada and the hamon is
suguha where nioikuchi is tightened, and Bo-shi also has the
characteristic of gently returning to a round shape. This form
continues until the end of the Muromachi period.

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Appraisal Quiz #718 (December 3rd, 2022)
Who made this sword do you think ?
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Blade Length:51.8cm or 20.39 inches
Sori:1.8cm or 0.70 inches
Mekugi hole:2
Width at the Hamachi:2.75cm or 1.08 inches
Width at the Kissaki:1.86cm or 0.73 inches
Kasane:0.65cm or inches
The weight of the sword:425gramsShape: The blade is slightly narrow,
normally thick with slightly deep Sori. Ko-Kissaki has slightly Fukura.
Well-shaped work. There is Bohi on the both sides.
Jigane: Dense Koitamehada, partially Masa flows.
Hamon: Gunome Midare from Hamachi, Choji comes in from the middle
and becomes Midare. Whole Hamon has Utsuri. Boshi is Midarekomi and turns back in a small circle.

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