During the period two groups of smiths worked in Province: the line and the Kongōbyōe line, named for the temple-associated smiths from whom the lineage descends. The trace the line to the Kongōbyōe Moritaka (初代金剛兵衛盛高) and frame this early chapter, Ko-Kongōbyōe, as the founding generations rather than the continuation. The smiths who anchor this phase in surviving work are Moritaka himself, present in a attributed to Kongō Hyōe Moritaka, and Reizei Sadamori (冷泉貞盛), called a smith of the Kongōbyōe line and traditionally traced back to Moritaka. The repeated documentary touchstone is Sadamori's signed inscribed "Chikushū Reizei Sadamori, Shōhei 25, first month, day," dated 1370, which fixes the active period of the early line and serves as the reference against which other works are appraised. One Moritaka attribution notes an example dated Shōhei 4 (1349), while the bulk of work bearing his name belongs to the period and later, which separates the early chapter described here from what follows.
What the describe again and again is a Yamato temperament read in both and . The forging is mixed with , often flowing toward near the edge, with the grain standing out (); adheres and enter as a relied-upon feature. The steel takes a somewhat dark, blackish with slight cloudiness, and a whitish or appears, conspicuously so in several of the wider . The temper is characteristically a narrow or , low in height, with a that tends toward tightness and ; along the come , uchi-noke, and a -like aspect, while and run modestly through and . The runs to with at the point, and grooves such as or are carved kaki-nagashi. A distinct sub-current within Sadamori's own work widens this manner: certain signed pieces show mixed with , abundant , and - in a arrangement, contrasted explicitly in one against the narrow- dated standard. This early restraint, dark steel, ground, and tight low is what the records use to set Ko-Kongōbyōe apart from the later Sue-Kongōbyōe production carried into the period.
For , the converge on a recognizable cluster: flowing leaning to , well-entered , blackish and whitish-cast steel showing the coloration the records tie to Kyūshū work, and a narrow whose tends to with and uchi-noke along the edge. Many surviving blades are in , broad with shallow and extended chū- to , while the signed evidence sits in and . Named smiths attached to this phase are Moritaka and Reizei Sadamori, the latter also written Reizen Sadamori in earlier records. On provenance, the certified Jūyō Bijutsuhin in 1939 was held by Koizumi Shinji of Kanagawa, and the line is documented in references including Imamura and Nihontō Taikan, with later attributions to Sadamori grounded on the Shōhei 25 standard.