Kenji Kakihara, the founder of this company, established Jonan Steel Shokai in Omori-kita, Ota-ku, Tokyo, to sell steel materials as a private management company.

Jonan Steel Mill Corporation purchased land at 5-13-35 Ryoke, Kawaguchi city, and started to construct a new rolling plant as a first phase of new mill constraction.

The company built a steel making plant as the second phase of the construction. This plant started production with a 20-ton electric furnace. The continuous production system from the steel-making process to the rolling process started. Capital was increased to ¥48 million with investment by Tokyo Small and Medium Business Investment & Consultation Co.,Ltd.

Authorized to use Japan Industrial Standard (JIS) Mark indication for reinforcing bar steel.

Continuous casting machine was installed.

The 20-ton electric furnace in the steel-making plant was replaced by a 40-ton electric furnace. Rationalization of the rolling line was done, which capabled 15,000 tons of production per month.

The steel making mill and the rolling mill achieved 25,000 tons production per month.

Rolling line and accuracy adjustment line were replaced by new lines. Both the steel-making mill and the rolling mill established 40,000-ton production systems.

The continuous casting machine in the steel-making plant was replaced by a new machine.

The finishing rolling machine in the rolling plant was replaced by a block mill.

The oxygen generator was replaced by a new one. The intermediate mill in the rolling plant was replaced by a block mill.

ISO 9002:1994 certified and registered.

The Purchasing Department purchased a iron scrap radioactive ray detection monitor.

The motors of the building dust collectors were changed to inverter-controlled motors to achieve energy saving.

The motors of the direct-suction dust collectors were changed to inverter-controlled motors to achieve energy saving.

Authorized to use Korean Industrial Standards (KS) for reinforcing bar steel. （KS D 3504）

Cooling bed and maintenance facility was renewed.

ISO 14001:2004 certified and registered.

Tempcore facility was installed.

Separately excited type flicker compensating device was replaced, and self-exciting type flicker compensating device was additionally installed.

Transformer for electric furnance was replaced by a new machine. Continous casting machine was replaced by a new one.

OHSAS 18001:2007 certified and registered.

Ladle preheating/drying equipment was replaced by a new one. Product cutting machine was replaced by a new machine.

Inverter equipment for rolling mill motors were renewed.

Rolling plant, slit roll reduction ratio updated.

ISO 14001:2015 certified and registered.

Electrode regulating control system was replaced.

ISO 9001:2015 certified and registered.

Cojet gas injection system was installed.

New company office completed.

Liquid oxygen equipment was installed.

Crop shear was replaced by a new one,and Inverter equipment for rolling mill motors were renewed.

ISO45001 certified and registered.

The oxygen generator was replaced by a new one.

Billet straightening device was installed.

Defects detector was installed.