Morinaga (守長) is recorded in sword reference works as a resident of in Province. He is traditionally said to have been the grandson of the second-generation Moriie and the son of Morishige of the lineage. His period is given as Shochu (1324-1326), and it is further said that there were two generations using the name Morinaga, with the second placed in Shohei (1346-1370). A contemporaneous smith writing the name with a variant character, Morinaga (守永), is confirmed by a bearing a date of 6 (1373), establishing his activity firmly in the period.
Surviving works by Morinaga display a forging of , at times with flowing tendency or standing grain; adheres, and appears. The is characteristically -laden: a lively with elements, mixed with , and enriched by frequent and . The shows with , ending in with a pointed tendency. As the observes, "at first glance the vigorous, exuberant with conspicuous does not readily appear to be work," and the features "bring it close to the group associated with ." This vigorous, -rich workmanship expresses the so-called Soden style, suggesting connections beyond the group to the lineages of Chogi and Motoshige. Morinaga appears to have been especially proficient at making , as multiple examples survive among his works.
Extant works by this maker are not particularly numerous, and those retaining his signature are rare. Each piece constitutes valuable material for study -- both for understanding the reach of the Soden idiom within the collateral lineages and for documenting a smith whose workmanship, in its exuberant and -like , reveals a broader network of stylistic influence than the genealogy alone would suggest.