Sunrock Oyodo was founded as a manufacturer of thumbtack materials and round nails under the company name of Oyodo Steel Co., Ltd. in 1941. Nissho Company (now Sojitz) invested in the company in 1954. Since 1970, it has consistently acquired manufacturers of bolts, iron wire, wire mesh and galvanized iron wire, and has developed to become a leading wire rod manufacturer with its production of 10,000 tonnes every month.

The company currently has four production facilities - at the headquarters, and in Harima, Kyushu, and Mie. It is engaged in the manufacturing and sale of wire rod and secondary wire rod products, including steel wire for cold heading (CH steel wire), iron wire, hard drawn steel wires, welded wire mesh, and fasteners (bolts).

CH steel wire, which is the primary product manufactured at the headquarters plant, is used in screws for cars, appliances, and construction. Because it is also used in important safety components in suspension parts for cars, extremely stringent quality standards are required.

The company produces approximately 4,000 tonnes of CH steel wire on a monthly basis and has become a major manufacturer. The iron wire produced at the plants in Harima and Kyushu is used for civil engineering and construction purposes, allows the company to hold the top share in western Japan.

President Kimio Hayashi proudly states, "We equip technology and facilities to meet the exact quality requirements of automotive manufacturers."

The Mid-term Consolidated Management Plan launched in 2003 was the impetus for increasing the level of quality. Large facility investments of approximately ¥1.5 billion were carried out, including the introduction of new equipment and major layout changes at plants. In December 2006, ¥800 million of the above amount was invested in completing the automated pickling line, which performs the important task of removing scale (iron oxide) from the surface of wire rod at the headquarters plant. This now operates as a completely modern fully automated line and provides a substantially improved level of efficiency.

The intention now is to focus on CH steel wire used in automotive screws, which have high added value and for which demand is rapidly increasing, using the sales network that has expanded since Metal One's establishment to the maximum and connecting this to a strategy to expand sales to Mitsubishi Motors Corporation, and others.