Showa Yokkaichi Sekiyu Co., Ltd. was established jointly by Showa Shell Sekiyu K.K. and Mitsubishi Corporation (MC) in 1957. The company is one of the largest oil refiners in Japan, equipped with highly sophisticated facilities. MC has 20 percent equity of the company and obtains certain volume of its own petroleum products through a consignment refining arrangement with the company. The company has a significant strategic role in MC's petroleum business activities.