The Social Democratic Party endorsed the appointment of Mizuho Fukushima, a lawyer-turned House of Councilors lawmaker, as secretary general Sunday, concluding its two-day convention in Tokyo.

The appointment of Fukushima, 45, means three of the SDP's key posts are now filled by women. Takako Doi, 72, is the president and Kiyomi Tsujimoto, 41, is policy affairs chief. It is the first time that the post of secretary general has been held in any major party by a woman.

The SDP tried to appoint Tsujimoto as secretary general, but the House of Representatives lawmaker declined the offer, and the party turned to Fukushima, the sources said.