Gen Nakatani, a former Self-Defense Force official, ran in the 1990 House of Representatives election as a candidate nominated by the Liberal Democratic Party (LDP) and won. From the time after he retired from the Ground Self-Defense Force until he ran for office, he served as a secretary under Kōichi Katō, Isamu Imai, and Kiichi Miyazawa.

In 2001, during the first Koizumi cabinet, he became the first graduate of the National Defense Academy and former office of the Ground Self-Defense Force to serve as the Director General of the Japan Defense Agency. Later, in 2014, he was the Minister of Defense Minister in charge of Security Legislation during Abe’s third cabinet.

In 2004, it was announced that the Self-Defense Force General Staff received a request from Nakatani to write a “draft of the Constitution.” This drift gives the Prime Minister the authority to command and supervise the military (軍隊), and stipulates the use of collective self-defense and the people’s obligation to defend the nation.