OPS-4 is a two-dimensional radar manufactured by Oki Electric Industry. It was installed as surface-search radar on the Maritime Self-Defense Force's self-defense ship. In the Maritime Self-Defense Force, the S-Band SO-8 was operated in the former Navy auxiliary boat that was in operation in the early days, but the Yashima-class minesweeper provided by the United States in the 1958 plan. The boat) was equipped with an X-band . The first mass-produced medium-sized minesweeper to be subsequently maintained was required to continue to be equipped with a domestic radar that operates in the X-band with short wavelengths and high resolution. This model was developed as a result.