TOKYO, Sept. 28 (Xinhua) -- Japan's junior ruling coalition partner Komeito officially endorsed Keiichi Ishii as the party's new chief at its convention on Saturday, marking the party's first leadership change in 15 years.

Ishii, 66, was the only candidate running in Komeito's leadership election after the party's long-time leader Natsuo Yamaguchi announced to step down upon the expiration of his eighth term.

The leadership change came a day after the Liberal Democratic Party elected veteran politician Shigeru Ishiba as the party's new leader. The two parties are set to reaffirm Monday that they will remain in coalition, Kyodo News reported.