Previous answer is
Mumei (Unsigned, attributed to Ko-Aoe).
無銘(古青江)

Features: From the end od the Hein period to the beginning of the Kamakura period is called Ko Aoe.
The style is similar to the neighboring province's Ko Bizen.
The Jigane is a unique and powerful charm.This is a robust piece from 818 years ago, attributed to Ko-Aoe, with a slightly thick kasane and a carved bōhi (groove) extending through the tang.

=====================================
Appraisal Quiz #830 (January 18th, 2025)
Who made this sword do you think ?
=====================================

Blade Length: 2 shaku 2 sun 4 bu, approximately 67.88 cm (26.73 in)
Curvature: 7 bu 5 rin, approximately 2.27 cm (0.89 in)
Mekugi Holes: 2
Width at Base (Motohaba): 2.91 cm (1.15 in)
Width at Tip (Sakihaba): 1.71 cm (0.67 in)
Thickness (Kasane): 0.48 cm (0.19 in)
Shape:The sword retains an almost ubu nakago (original tang).
It has a deep curvature with torii sori and a typical kissaki.
Jigane:The surface has a dense ko-itame hada, resembling a near-muji appearance, with a visible utsuri effect.
Hamon: The hamon is a combination of gunome-midare and choji-midare with vibrant activities in the ha.
The boshi is small, rounded, and gently returns.

=====================================

Answer will be posted at next Appraisal Quiz.

=====================================

(Please acknowledge not replying to mail about Appraisal Quiz by our convenience.)