Toshitsugu is a smith of the school of Bicchu Province, variously transmitted as a son of Moritsugu or of Tsugie. Sword compendia place his active period around the Kenryaku era (1211–1214), situating him among the early generation of the lineage, which is traditionally held to have begun with Yasutsugu around the Joan era (1171–1175). Works by smiths dating from the end of the period through roughly the mid- period are referred to in particular as . Extant signed works by Toshitsugu are exceedingly few, and it is noted that smiths characteristically cut their signatures on the side of the tang. A later Toshitsugu, active during the mid- period, is documented at Manju Honjo in the province with a dated inscription of Enbun 4 (1359).
The style of , including that of Toshitsugu, commonly shows a forging in which stands out within the and tends toward , producing what is termed a -jo (crepe-like) texture; many examples also exhibit patchy areas in the ground. The ranges from calm -toned tempers to those mixed with , , and small , and in all cases adheres well. Fine attaches thickly with , and activities such as and appear within the temper. Near the edge one observes suji-, while toward the ridge stands, together producing an effect reminiscent of . The may show a tendency or appear bright and clear.
Overall, compared with contemporary works, Toshitsugu's blades present a somewhat more subdued and restrained character — a profound, astringent depth of flavor that the describes as tastefully austere. His signed are praised for dignified form with high and compact , and for forging of outstanding quality. The combination of fine workmanship, abundant and activities, and sound preservation across surviving examples confirms Toshitsugu's importance within the tradition and his value for the study of early -period Bicchu smithing.