Obayashi Corp. engages in the construction and real estate business. It operates through the following segments: Domestic Building Construction, Overseas Building Construction, Domestic Civil Engineering, Overseas Civil Engineering, Real Estate, and Others. The Domestic Building Construction segment engages in building construction contracts and related businesses within Japan. The Overseas Building Construction segment engages in building construction contracts and related businesses outside Japan. The Domestic Civil Engineering segment handles civil engineering construction contracts and related businesses within Japan. The Overseas Civil Engineering segment deals with civil engineering construction contracts and related businesses outside Japan. The Real Estate segment handles the purchase, sale, development and rent of real estate properties. The Others segment engages in Private Finance Initiative (PFI), finance, renewable energy, and operation of golf courses. The company was fou