TOKYO, Sept. 27 (Xinhua) -- Former Defense Minister Shigeru Ishiba won Japan's ruling Liberal Democratic Party (LDP) presidential election on Friday, virtually ensuring that he will become the country's next prime minister.

As the LDP-led coalition constitutes a majority in both chambers of the parliament in Japan, the new party leader is almost certain to be elected prime minister in the extraordinary Diet session scheduled to be held on Oct. 1, succeeding the incumbent Fumio Kishida.