Japanese Prime Minister Shinzo Abe on Wednesday picked a close confidante with staunchly nationalist views as the new defence minister, a move likely to raise concerns in China and South Korea.

Lawyer-turned-politician Tomomi Inada, 57, was formerly policy chief of Abe's ruling Liberal Democratic Party and shares his hawkish views on Japan's 20th century history.

She becomes the second woman to oversee the defence ministry after Yuriko Koike, who served briefly in 2007 and was elected governor of Tokyo on Sunday.

Inada, a four-term lawmaker who replaces Gen Nakatani, was named to the post as part of a partial cabinet after the LDP's big win in upper house parliamentary elections last month.

Her appointment came on the same day North Korea, a major security headache for Japan, fired a ballistic missile that landed just 250 kilometres (155 miles) off its coast -- hitting Japanese-controlled waters for the first time.

Inada, a mother of two, has a history of irritating Asian neighbours such as China and South Korea.

She has been a regular visitor to Tokyo's contentious Yasukuni war shrine and has played a leading role in an LDP study group launched last year to review Japan's history, reportedly taking up controversial issues such as the Nanjing massacre and the Tokyo war crimes trials.

In 2011 she and two other conservative Japanese politicians had planned to visit Ulleung island, the closest South Korean territory to the Seoul-controlled Dokdo islands in the Sea of Japan (East Sea), which are known in Japan as Takeshima.

They flew to a Seoul airport to push Tokyo's claim to the disputed islands and refused to fly back home for hours after their entry to South Korea was denied.

Japan is also embroiled in long-running territorial disputes with China and Russia.

Inada appeared to take a careful approach in initial remarks Wednesday.

"I will give my utmost in order to ensure peace and security by cooperating with nations that share interests and values," she told reporters, specifically citing Japan's security alliance with the United States.

Asked whether she planned to visit the Yasukuni Shrine on August 15, the anniversary of Japan's World War II surrender, she declined to give a straight answer, saying that such a decision is a "matter of the heart".

In the cabinet revamp announced by Chief Cabinet Secretary Yoshihide Suga, Abe left most key posts untouched. Fumio Kishida, the foreign minister, and Taro Aso, finance minister and deputy prime minister, were among those keeping their jobs.

Abe also tapped Suga, his right-hand man, to stay on.

Besides Inada, other new picks include Hiroshige Seko for economy, trade and industry minister and previous environment minister Tamayo Marukawa as the minister in charge of the 2020 Tokyo Olympics.