Sumitomo Electric Optifrontier Co., Ltd.


Company Profile

Company Profile

Company name Sumitomo Electric Optifrontier Co., Ltd.
Founded On May 15, 1915, Predecessor of Toyokuni Electric Cable, Co., Ltd., started its operation as Toyokuni Electric Cable Factory.
Business Started as SEOF December 23, 1939
Industry Manufacturing industry
Business Manufacturing optical communication and device products
  • Optical fiber cable and cord products
  • Optical connector products
  • Optical network products
  • Optical communication tools
  • Precision components
Representative President Suetsugu Yoshiyuki
Capital 660 million yen
Shareholder Sumitomo Electric Industries, Ltd.
Number of employees 900 (consolidated)
Business bases [Head office] Yokohama (Inside Sumitomo Electric Yokohama Works)
[Offices] Yokohama, Saitama, Shonan, Suwa
[Sales offices] Tokyo, Osaka
Group company Opti Frontier Manufacturing Co., Ltd.


A Brief History of (Former) Toyokuni Electric Cable Co., Ltd.
1915 Toyokuni Electric Cable, Co., Ltd., was founded in present Negishi, Taito-ku, Tokyo. Started manufacturing electric cords/cables.
1939 Sasaki Manufacturer Co., Ltd. was established in present Hamamatsu-Cho, Minato-ku, Tokyo. Started manufacturing magnet wires and rubber wires.
1962 The factory of Sasaki Manufacturer Co., Ltd. relocated to Gyoda-shi in Saitama.
1967 Sumitomo Electric Industries, Ltd. participated in management.
1973 Due to the merger of the two companies on April 1, the company name was changed to Toyokuni Sasaki Densen Co., Ltd. and the company was established with a capital of 200 million yen.
1975 Started production of harnesses for houses and buildings.
1979 Headquarters relocated from Torano-Mon, Minato-ku to Minami-Ikebukuro, Toshima-ku, in Tokyo.
1983 TSE Inc. was established.
1986 On October 1, the company name was changed: Toyokuni Electric Cable, Co., Ltd.
1987 A new factory for optical fiber cables started its operation.
1989 Increase in capital: 661,605,050 yen
Saitama Toyokuni Inc. was established.*
1990 Yamanashi Toyokuni Inc.* and TKK Inc.** were established.
1991 Started manufacturing connectorized optical cables.
Tohoku Toyokuni Inc. was established.*
1994 T&D Inc. was established.**
1995 Started delivery of in-station optical cable to Nippon Telegraph and Telephone Corporation.
1996 Toyokuni Engineering Services Inc. was established.** Obtained ISO 9001 certification.
1997 Kansai Toyokuni Inc. was established.* Obtained NQAS (NTT's New Quality Assurance System) certification
1999 Started manufacturing optical fiber couplers.
2000 Obtained ISO 14001 certification.
2001 Chichibu Toyokuni Inc. was established.**
2002 Shikoku Toyokuni Inc. was established.*
Power cable production ended, optical cable business expanded
2008 Sumitomo Electric Industries, Ltd. wholly owned subsidiary
2010 Residential/building harness business transferred to Sumitomo Electric Industrial Wire & Cable Inc.
Toyokuni Electric Cable Co., Ltd. and Sumiden High Precision Co., Ltd. merged, SEI Optifrontier Co., Ltd. began service
2020 Changed company name to Sumitomo Electric Optifrontier Co., Ltd.

*: Subsidiaries for information communication-related industries
**: Subsidiaries for housing and building-related industries.

A Brief History of (Former) Sumiden High Precision Co., Ltd.
1938 Established as Showa Kikai Kogu Co., Ltd.
Started manufacturing cutting tools for airplane production.
1942 Suwa Plant was opened in Ochiai-mura, (present Fujimi-machi), Suwa-gun, Nagano.
1947 Started manufacturing adjustment tools for communications equipment under contract with Teishinsho or former Japanese Ministry of Posts and Telecommunications.
1956 Started manufacturing coaxial terminals and connection tools for coaxial cables.
1978 Sumitomo Electric Industries, Ltd. participated in management.
1983 Started delivering fiber optic tools, optical connectors, and cords with optical connectors to Nippon Telegraph & Telephone Public Corporation (currently NTT).
1984 - 1991 Started delivering to Nippon Telegraph & Telephone Public Corporation (currently NTT): connector connection tools for digital switching machines, fire resistance covers, fiber detectors for cable tunnels, evacuation lights, connectors for GI optical cables, and SC type optical connectors, etc.
1992 Headquarters relocated from Meguro-ku, Tokyo, to Chigasaki-shi, Kanagawa.
Changed the company name to Sumiden High Precision Co., Ltd.
Started manufacturing MT connectors.
Started consignment manufacturing mechatronics products.
1997 Obtained ISO 9001 certification and NQAS certification (NTT's New Quality Assurance System)
2000 Started manufacturing optical receiver/transmitter products. Obtained ISO 14001 certification.
2001 Completed the construction of Shonan Plant No. 2.
2002 Started the operations of Yokohama Plant.
2003 Started manufacturing optical modules and optical receptacles.
2004 Expanded the operations of Suwa Plant.
2007 Opened Fujisawa Center.
2008 Celebrated the 70th anniversary of its foundation.
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