Arimitsu (在光) was a swordsmith of the tradition working at . Reference works enumerate six smiths bearing this name. Among the representative masters are a Zaiko who held the honorary title Izumo no Kami, active chiefly around the Eisho era (1504--1521), and another known as Kurozaemon no Jo, active around the Tenbun era (1532--1555). Izumo no Kami Zaiko stands as a figure of particular note: just as Seki produced Izumi no Kami Kanesada, so too in the period produced smiths granted court titles, yet among works by smiths whose names include the character mitsu (光), examples bearing such a conferred title are exceedingly few. The Kurozaemon line is documented through commissions that record both the smith's common title and the names of patrons, offering valuable evidence of the workshop's clientele during the final decades of production.
The workmanship of the Arimitsu line displays the characteristic of at its most accomplished. The forging is tightly packed mixed with , with very fine , delicate , and vivid standing out distinctly. The tempering centers on with a widened profile (), intermixed with , , , and angular forms, in places becoming a compound () . Within this tempered edge, and are active, with adhering to a tightened and fine and partial running through. Certain works display and small , imparting further variation. The Kurozaemon generation also produced blades in mixed with , showing the broader stylistic range available within the lineage. Blade forms are typically compact, with strong and short tangs that do not taper -- features constituting the classic shape.
The consistently praises works of this lineage for their careful execution and bright, clear impression in both and . Blades retain ample and are frequently noted as preserved in condition. The forging is described as well-kneaded, and the is characteristically -- clear and bright. Since extant works by these smiths are comparatively few, each authenticated example is regarded as fully demonstrating the high level of technique within the Arimitsu line and is especially precious as reference material, with dated inscriptions providing important documentary value for the study of late -period production.