Muneyoshi is a smith of the Ko-, the earliest generation of the , working in the opening years of the period. The published sources place him at the threshold of the school: drawing on the Meizukushi Taizen, they record that 'Muneyoshi belonged to the Ko-', that he was a son of Munekuni and married into the house of Norimune, 'son-in-law of Norimune, founder of the ', and that he served alongside Norimune and Sukemune as one of the , the swordsmiths in monthly attendance on Retired Emperor Go-Toba. One Jūyō Bijutsuhin entry sets him in the Jōkyū years and the so-called July group; a gives him the Shōji-era rotation. His is among the first hands to carry the manner forward after Norimune, who signed only the single character .
His blades are , slender and well-proportioned, several retaining a high -zori and strong even where shortened. Over an , at times a closely packed and mixed with , the steel carries a thick and a vivid that stands out clearly on every signed example. The temper is the tell of his hand: not the full clove-flower of the later school but a -toned small , into which he sets and , with abundant and , well adhered, and fine and running through. The runs straight into a small or finishes in a -like sweep.
The is the constant. with and the bright of old steel appears on each blade, sometimes with entering frequently and the grain standing a little; where the forging tightens into the only grows clearer. Over that the stays comparatively calm. Where one piece widens into a more flamboyant toward the middle with , the body of the temper remains a small irregular line, deep in and , the activity carried in and rather than in towering clusters.
The published sources draw a careful distinction within his own work. Examining extant signed pieces, they find that the manner of the signature differs from blade to blade, and that the workmanship divides in two: some are archaic and classical in a mode, others mix in for a somewhat more decorative feeling. From this they infer that 'there were multiple smiths' using the one name Muneyoshi. The point recurs across his entries and is the central scholarly question around him, left open for further study.
What separates the Ko- Muneyoshi from both his neighbours is exactly what the judges name. He is set apart from the flamboyant of the mid- to late- , his temper read instead as 'an archaic register, unlike the flamboyant of the mid-, with the old colour of its period'; and he is held apart from the plainer smiths by the brightness of his and the gathering of on his edge. He stands before the school's great flowering at Fukuoka, Yoshioka and Katayama, the quiet root from which the most brilliant of the traditions grew.
For the collector he is a rare early name. Fujishiro grades him Jō-jō . He has no National Treasures; his record runs instead through Important Cultural Properties, Jūyō Bijutsuhin and the higher modern tiers, and the published commentary calls one shortened 'foremost among works by the hand'. His blades are preserved in long-held collections and institutions grounded in their own provenance, the Mōri family among the houses, the Seikadō Bunko from the Iwasaki collection, and the Kurokawa Institute of Ancient Cultures, with a pair held at Atsuta Jingū. Only a small number fall in the and tiers, so a signed Ko- Muneyoshi comes to light only seldom, and a privately held example is a notable thing for a collector to encounter, a document of how the began.