SUN - The company appeared soon after World War II as Sun Kōki K.K. (サン光機㈱, San Kōki). It was a successor of the company Gojō Kōki Seisakusho, maker of the K.O.L. lenses, which ceased its activity in 1945. Early Sun lenses had the brand names Xebec and Sola, inherited from the K.O.L. period. In the 1950s or 1960s, the company was using the English name Sun Optical Co., Ltd. and was based in the city of Ichikawa (in the Chiba Prefecture, at the East of Tokyo). Its logo was an elongated "S" crossed by two brackets.

Sun made interchangeable lenses in various mounts, for still and cine cameras. It changed its name to Gotō Sun (ゴトー・サン) at some time, perhaps in the 1970s, and no later than 1981. At that period, it manufactured the Orinox binocular camera, also sold as the Tasco Bino/Cam.

The company was still in existence in 1983, and disappeared in the 1980s. There is significant evidence to suggest that Sun was absorbed into Goyō Kōgaku Shōji Y.K. (五洋光学商事有限会社, also known as Goyo Optical Inc.), some time in the late 1980s. Goyo Optical was founded in 1976[8] and produces mainly CCTV and industrial lenses; however its 50mm f/0.95 lens has recently (2010) been sold under the Noktor brand in Micro Four Thirds mount. The Noktor brand is marketed by Noktor, LLC, Atlanta/USA.