Kowa, a Japanese optical and pharmaceutical company, produced a short-lived line of 35mm SLR cameras and interchangeable lenses in the 1960s and early 1970s, including the Kowa SE and Kowa SET bodies. The 135mm f/4 was a moderate telephoto within that system's lens range before Kowa withdrew from cameras.
Kowa lenses used the marque's own proprietary bayonet rather than a shared industry-standard fitting, so they only fit Kowa's own bodies without an adapter. The 135mm f/4 offered a portrait-to-telephoto focal length within a compact lineup that also included wide-angle and macro options.
Kowa's SLR lenses are generally well regarded among collectors for build and optical performance relative to their limited production runs, though the proprietary mount restricts use to Kowa bodies. The 135mm f/4 follows the same ethos as the rest of the range, prioritising compact correction over sheer speed.
Kowa camera equipment is scarce in the used market since the company ceased photographic production in the 1970s, and the proprietary mount limits appeal mostly to Kowa-system collectors. Confirm the lens mates with the specific body and inspect for age-related haze.