A series of public and secret loans signed by Duan government and Japan from June 5438, 2007 to June 65438, 2008. The Duan government borrowed a series of money from Japan through Nishihara Jisaburo. The largest eight loans totaled 654.38 billion+450 million yen, which was called "Nishihara Loan". In order to get the money, Duan sold a series of sovereignty of China in Northeast China, such as building railways, deforestation and mining, to Japan, which laid a hidden danger for Japan's full occupation of Northeast China.