Japan's fourth-biggest oil refiner TonenGeneral Sekiyu K.K. announced Wednesday that it will acquire an 89.9 percent stake in Mitsui Oil Co. for JPY 24.9 billion (USD 242 million). TonenGeneral will buy Mitsui Oil's share from a major trading house Mitsui and Co., on Feb. 4, the Tokyo-based refiner said in a statement. "TonenGeneral plans to enhance its core businesses by integrating the newly acquired businesses into the existing ones, e.g. expansion and strengthening of the sales network and optimization of the supply system," the statement said. With the acquisition, TonenGeneral is set to become Japan's third-largest refiner in terms of sales following JX Holdings Inc. and Idemitsu Kosan Co. In addition, Mitsui Co. said it has also reached an agreement with Exxon Mobile Bay Limited Partnership, a 100 percent subsidiary of Exxon Mobil Corp., to purchase a 6.4 percent stake of TonenGeneral for JPY 33.6 billion (USD 327 million). "Mitsui will seek to deepen its cooperative relationship with TonenGeneral through the continued transaction of crude oil and petroleum products," the trading giant said in a separate statement