Idemitsu Kosan, Japan’s oil refiner, formally took over its smaller peer Showa Shell Sekiyu, cementing its position as the country’s No. 2 producer. The deal valued Showa Shell at $308m. The deal between Idemitsu, already ranked second by sales, and Showa Shell, ranked fourth, became official with the start of Japan’s April-March fiscal year. The new company, formed after a deal long-delayed by opposition from Idemitsu’s founding family, has annual sales of more than $52bn.