Sōshū Hiromasa
A Sagami smith of the Muromachi period, of the late Sōshū tradition; his blades have been compared with those of Bizen of the Ōei era.
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Hiromasa worked in Sagami (Sōshū) in the Muromachi period, when Masamune’s manner was still alive in the province. The Japanese Wikipedia counts him among the Sōshū-den smiths of that time, and Markus Sesko names him among those of Sōshū in his series on kantei by the shape of the blade. The blog Studying Japanese Swords compares his work with that of Bizen of the Ōei era (1394-1428) and points out that a faint bō-utsuri can be seen in the steel.
There are no years, teacher or designated works in publishable sources, and some move him back to the Nanbokuchō without clear support. He is not Wakasa no Kami Hiromasa, a shintō smith of Settsu who writes his name with other characters.