Bain Capital said in a statement it planned to launch a tender offer to buy all of the shares in Showa Aircraft at 2,129 yen per share. Shareholders would receive an additional 631 yen if they tender their shares, which makes the entire deal worth 90 billion yen, Bain said.
Showa Aircraft shares closed at 2,537 yen on Thursday.
Mitsui E&S has agreed to sell all of its shares in Showa Aircraft, which accounts for 65.53% of the company, Bain said. It aims to buy at least 66.67% of the outstanding shares.
Mitsui E&S is selling Showa Aircraft as it tries to shore up its balance sheet, which suffered from losses of about 150 billion yen incurred in 2018 and 2019 from a project to build a coal-fired generating plant in Indonesia.
Mitsui E&S has already sold its plant engineering and solar power businesses.
Bain became better known in Japan after it led an $18 billion investment in Toshiba Memory, the world's second-largest maker of NAND memory chips, now known as Kioxia, which was spun off from Toshiba Corp.
(Reporting by Junko Fujita; Editing by Jan Harvey and Barbara Lewis)