Tomokiyo was a swordsmith of the school, one of the five major groups of the Yamato tradition, which flourished from the late period through the era with Kuniyuki as its founder. Reference works state that the first-generation Tomokiyo was a son of Kuniyuki, active around the Gen'o era, and that three generations bore the name, spanning the Ryakuo and Oei eras. The smiths of -dera were originally artisans attached to the temple, which helps explain why extant signed works are exceedingly few and the majority of attributions are made on unsigned tangs. A partially inscribed reading "Yamato no Tomo" (with the remainder cut away), designated - at the 13th Session, serves as the principal reference piece for this smith. A separate Nio Tomokiyo, active around the Oei era, represents a related but distinct line descended from the Yamato tradition.
In the forge, Tomokiyo's work displays mixed with , partially flowing and tending toward ; fine lies thickly, with frequent , and the steel is notably clear. The is characteristically mixed with small , with and ; attaches thickly, and along the edge appear , , , and uchi-noke, while and run frequently. The is bright and clear. In these features, the school's distinctive traits in both and are strongly evident. The typically enters in with vigorous , sometimes becoming flame-like in character.
The broad construction with ample and the Enbun-Joji-type silhouette culminating in an place Tomokiyo's work firmly within the period. The internal activities within the hardened edge are frequently praised as outstanding, and pieces attributed to this smith characteristically show no slackness in the , with exceptionally good states of preservation.