A typhoon has been drenching parts of Japan as the country heads to the polls after Prime Minister Shinzo Abe called a snap election in the face of the rising threat from North Korea.
Mr Abe called the election amid rebounding approval ratings after a record low over the summer and with the opposition largely in disarray.
He is predicted to win a majority, after the opposition fell apart.
A challenge from Tokyo governor Yuriko Koike appears to be fizzling out.
One observer described voting for Mr Abe's Liberal Democratic Party as TINA, or "there is no alternative", the BBC's Tokyo correspondent Rupert Wingfield-Hayes reports.
Mr Abe is hoping his party will win a two-thirds majority, allowing him to make constitutional changes. In particular, he wants to change Japan's self-defence force into a national army for the first time since the World War II.
What impact, if any, Typhoon Lan will have on turnout remains to be seen. The category four storm brought strong winds and heavy rain to the south of the country, causing flights to be cancelled and rail services to be disrupted.
It is expected to blow into the Tokyo area early on Monday, the Japan Meteorological Agency said.
Mr Abe announced the election on 25 September, saying he needed a fresh mandate in order to deal with the "national crises" facing Japan.
The crises include North Korea, which has threatened to "sink" Japan into the sea. Pyongyang has also fired two missiles over Hokkaido, an island to the north.
Other areas up for debate in the election are the post-Fukushima nuclear policy and the issue of tax.
The polls close at 20:00 local time (11:00 GMT).