TOKYO — Denny Tamaki, the son of a Japanese mother and a United States Marine, became the first mixed-race governor in Japan on Sunday after winning a close election in Okinawa, a southern archipelago heavily populated by American military installations.

His victory poses a setback to plans by the Japanese government and the United States to transfer a busy Marine air base on Okinawa from the city of Ginowan to a less populated coastal area on the island.

Mr. Tamaki wants the base moved out of Okinawa altogether. His opponent, Atsushi Sakima, who was backed by Japan’s ruling Liberal Democratic Party, was until recently the mayor of Ginowan and supported the base’s transfer.

Mr. Tamaki, 58, succeeds Takeshi Onaga, an outspoken critic of the American bases, who died in August from complications of pancreatic cancer.