Previous answer is
　 Mumei (Unsigned) (Nio)
無銘(二王)

Features: Nio school active around the mid-Kamakura period, who regarded Nin'ō Kiyotsuna as their ancestor, produced swords with straight Hamon and visible reflections.

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Appraisal Quiz #781 (February 10th, 2024)
Who made this sword do you think ?
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Blade length: 80.6 cm (31.73 in).
Curvature: 2.6 cm (1.02 in).
Mekugi holes: 1.
Width at base: 3.04 cm (1.20 in).
Width at the tip: 1.65 cm (0.65 in).
Thickness of rim: 0.86 cm (0.34 in).
Shape: The sword has a normal width, thick Kasane, and a large curvature, making it a long blade.
Jigane: Fine ko-itame hada well worked with a clear jigane and visible steel.
Hamon: The hamon is a lively mix of nie with irregular patterns, deep nioiguchi, with activities such as ashi and yō, including sunagashi and kinsuji.

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