SEI Optifrontier is a comprehensive manufacturer of optical network products, optical modules and high-precision processing parts.

Sumitomo Electric Group

Yokohama/Headquarters Area

Shonan Area (Shonan Works)

Suwa Area (Suwa Works)

Saitama Area (Saitama Works)

Aomori Area (Aomori Factory)

Tanabe Area (Tanabe Factory)

Higashi-Kagawa Area (Higashi-Kagawa Factory)