Onaga was elected to the governorship defeating the incumbent, Hirokazu Nakaima. His campaign was based on opposing the relocation of the Futenma Base within Okinawa, and ending U.S. military presence in Okinawa. In October 2015, Onaga revoked the land reclamation permit needed for continued work on the base. This stance also made him a target of regular smear campaign by some Japanese right-wing activists on the internet. For example, in April 2015, Toshio Tamogami, former chief of the Japanese Air Self-Defense Force tweeted that Onaga's daughter had studied in Beijing and married a Chinese Communist Party (CCP) official, an allegation intended to link Onaga and his opposition to the American bases in Okinawa to the CCP.
