Japan's main opposition Democratic Party's new leader Renho (L) reaches out to shakes hands with former party leader Katsuya Okada after she was elected party leader at the party plenary meeting in Tokyo, Japan September 15, 2016. REUTERS/Toru Hanai 

Japan's main opposition Democratic Party's new leader Renho (C) reaches out to shakes hands with former party leaders Seiji Maehara (L) and Katsuya Okada after she was elected party leader at the party plenary meeting in Tokyo, Japan September 15, 2016. REUTERS/Toru Hanai 

Japan's main opposition Democratic Party's new leader Renho (2nd L) raises her hands with her party lawmakers including former leaders Seiji Maehara (L) and Katsuya Okada (2nd R) after she was elected party leader at the party plenary meeting in Tokyo, Japan September 15, 2016. REUTERS/Toru Hanai TPX IMAGES OF THE DAY

Japan's main opposition Democratic Party's new leader Renho (2nd L) raises her hands with her party lawmakers including former leaders Seiji Maehara (L) and Katsuya Okada (2nd R) after she was elected party leader at the party plenary meeting in Tokyo, Japan September 15, 2016. REUTERS/Toru Hanai 

Japan's opposition Democratic Party leader Katsuya Okada (R) is taken a selfie with voters on the last day of campaigning for the July 10 upper house election at Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada (2nd R) shakes hands with a voter on the last day of campaigning for the July 10 upper house election at Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada (C) delivers a speech to voters on the last day of campaigning for the July 10 upper house election near Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada (R) is seen through umbrellas as he delivers a speech to voters on the last day of campaigning for the July 10 upper house election near Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada (C) delivers a speech to voters on the last day of campaigning for the July 10 upper house election at Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada (3rd L) shakes hands with a voter on the last day of campaigning for the July 10 upper house election at Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada (C) shakes hands with a voter on the last day of campaigning for the July 10 upper house election at Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada (2nd L) talks with voters on the last day of campaigning for the July 10 upper house election at Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada speaks to voters on the last day of campaigning for the July 10 upper house election at Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's opposition Democratic Party leader Katsuya Okada is seen through umbrellas as he speaks to voters on the last day of campaigning for the July 10 upper house election near Tsukiji fish market in Tokyo, Japan July 9, 2016. REUTERS/Issei Kato 

Japan's Prime Minister and leader of the ruling Liberal Democratic Party (LDP) Shinzo Abe (L) and the leader of the Democratic Party Katsuya Okada attend a debate with rival party leaders ahead of the July 10 upper house election in Tokyo, Japan, June 21, 2016. REUTERS/Thomas Peter 

Japan's Prime Minister and leader of the ruling Liberal Democratic Party (LDP) Shinzo Abe (L) and the leader of the Democratic Party Katsuya Okada attend a debate with rival party leaders ahead of the July 10 upper house election in Tokyo, Japan, June 21, 2016. REUTERS/Thomas Peter 

Japan's Prime Minister and leader of the ruling Liberal Democratic Party (LDP) Shinzo Abe (L) and the leader of the Democratic Party Katsuya Okada (R) attend a debate with rival party leaders ahead of July 10 upper house election in Tokyo, Japan, June 21, 2016. REUTERS/Thomas Peter 

Japan's Prime Minister and leader of the ruling Liberal Democratic Party (LDP) Shinzo Abe (C), the leader of the Democratic Party Katsuya Okada (R) and Komeito party leader, Natsuo Yamaguchi, attend a debate with rival party leaders ahead of July 10 upper house election in Tokyo, Japan, June 21, 2016. REUTERS/Thomas Peter 

Japan's Prime Minister and leader of the ruling Liberal Democratic Party (LDP) Shinzo Abe (C), the leader of the Democratic Party Katsuya Okada (R) and Komeito party leader, Natsuo Yamaguchi, attend a debate with rival party leaders ahead of July 10 upper house election in Tokyo, Japan, June 21, 2016. REUTERS/Thomas Peter 

Japan's Prime Minister and leader of the ruling Liberal Democratic Party (LDP) Shinzo Abe (L) and Katsuya Okada, leader of the opposition Democratic Party, attend a debate with rival party leaders ahead of July 10 upper house election in Tokyo, Japan, June 21, 2016. REUTERS/Thomas Peter 

Japan's Prime Minister and leader of the ruling Liberal Democratic Party (LDP) Shinzo Abe (L) and Katsuya Okada, leader of the opposition Democratic Party, attend a debate with rival party leaders ahead of July 10 upper house election in Tokyo, Japan, June 21, 2016. REUTERS/Thomas Peter 

Japan's opposition Democratic Party leader Katsuya Okada attends a parliament session for a no-confidence motion against Prime Minister Shinzo Abe's cabinet, submitted by four opposition parties at the parliament in Tokyo, Japan May 31, 2016. REUTERS/Toru Hanai 

Japan's opposition Democratic Party leader Katsuya Okada speaks in front of Prime Minister Shinzo Abe and Deputy Prime Minister and Finance Minister Taro Aso during a parliament session for a no-confidence motion against Abe's cabinet, submitted by four opposition parties at the parliament in Tokyo, Japan May 31, 2016. REUTERS/Toru Hanai 

Leader of Japan's opposition Democratic Party of Japan, Katsuya Okada looks on at the plenary session for a vote on security bills at the Upper House of the parliament in Tokyo, Japan, September 19, 2015. Japan's parliament voted into law on Saturday a defence policy shift that could let troops fight overseas for the first time since 1945, a milestone in Prime Minister Shinzo Abe's push to loosen the limits of the pacifist constitution on the military. REUTERS/Toru Hanai 

Leader of Japan's opposition Democratic Party of Japan Katsuya Okada poses for a photo after an interview with Reuters in Tokyo, July 7, 2015. Japanese Prime Minister Shinzo Abe will be taking a big risk if he pushes through a dramatic change in security policy despite objections from most citizens, who want a better explanation why the change is needed, Okada said on Tuesday. The words on posters read 'start with the regions' (L) and 'start with livelihoods'. REUTERS/Toru Hanai

Leader of Japan's opposition Democratic Party of Japan Katsuya Okada poses for a photo after an interview with Reuters in Tokyo, July 7, 2015. Japanese Prime Minister Shinzo Abe will be taking a big risk if he pushes through a dramatic change in security policy despite objections from most citizens, who want a better explanation why the change is needed, Okada said on Tuesday. The words on posters read 'start with the regions' (L) and 'start with livelihoods'. REUTERS/Toru Hanai

Leader of Japan's opposition Democratic Party of Japan Katsuya Okada speaks during an interview with Reuters in Tokyo, July 7, 2015. Japanese Prime Minister Shinzo Abe will be taking a big risk if he pushes through a dramatic change in security policy despite objections from most citizens, who want a better explanation why the change is needed, Okada said on Tuesday. REUTERS/Toru Hanai

Leader of Japan's opposition Democratic Party of Japan Katsuya Okada speaks during an interview with Reuters in Tokyo, July 7, 2015. Japanese Prime Minister Shinzo Abe will be taking a big risk if he pushes through a dramatic change in security policy despite objections from most citizens, who want a better explanation why the change is needed, Okada said on Tuesday. REUTERS/Toru Hanai

Japan's Deputy Prime Minister Katsuya Okada, a Democratic Party of Japan (DPJ) lawmaker, looks at candidate names as he leaves a news conference at his party's election headquarters in Tokyo December 16, 2012. Japan's conservative Liberal Democratic Party (LDP) surged back to power in an election on Sunday just three years after a devastating defeat, giving ex-Prime Minister Shinzo Abe a chance to push his hawkish security agenda and radical economic recipe. Voters had expressed disappointment with Noda's DPJ, which swept to power in 2009 promising to pay more heed to consumers than companies and reduce bureaucrats' control of policymaking. REUTERS/Issei Kato (JAPAN - Tags: ELECTIONS POLITICS) 

Japan's Prime Minister Yoshihiko Noda (R) scratches his head next to Deputy Prime Minister Katsuya Okada (C) and Japan's Trade Minister Yukio Edano as they attend a lower house plenary session at the parliament in Tokyo November 15, 2012. Noda is set to dissolve parliament's lower house on Friday for a snap election next month, which is likely to cost him his job and return to power a party that has governed Japan for most of the past 50 years. REUTERS/Yuriko Nakao (JAPAN - Tags: POLITICS BUSINESS) 

Japan's Prime Minister Yoshihiko Noda raises his hands next to Deputy Prime Minister Katsuya Okada as they attend the lower house budget committee meeting in Tokyo November 12, 2012. Under growing opposition pressure to keep a promise to call an election "soon", Noda looks to be leaning toward calling a vote as early as next month, after pledging backing for a controversial U.S.-led free trade pact. REUTERS/Yuriko Nakao (JAPAN - Tags: BUSINESS EMPLOYMENT POLITICS) 

Japan's newly appointed Education, Culture, Sports, Science and Technology Minister Makiko Tanaka (C) stands with Foreign Minister Koichiro Gemba (R), Deputy Prime Minister Katsuya Okada (2nd R), newly appointed National Policy Minister Seiji Maehara (2nd L) and Trade Minister Yukio Edano (L) after a photo session with Japan's Prime Minister Yoshihiko Noda (not in picture) and other cabinet members after their first cabinet meeting at the premier's official residence in Tokyo October 1, 2012. REUTERS/Kim Kyung-Hoon (JAPAN - Tags: POLITICS BUSINESS) 

Japan's Prime Minister Yoshihiko Noda (2nd R), Deputy Prime Minister Katsuya Okada, (R), newly appointed National Policy Minister Seiji Maehara (2nd L) and Trade Minister Yukio Edano prepare for a photo session with other cabinet members after their first cabinet meeting at the premier's official residence in Tokyo October 1, 2012. REUTERS/Kim Kyung-Hoon (JAPAN - Tags: POLITICS BUSINESS) 

Japan's Prime Minister Yoshihiko Noda (top L) is seated with his cabinet members during the lower house plenary session at the parliament in Tokyo June 26, 2012. Japan's lower house approved a plan to double the sales tax on Tuesday to help curb the nation's snowballing debt following a breakthrough deal between the ruling bloc and the opposition. But the compromise, which helped Prime Minister Yoshihiko Noda end months of policy gridlock, could split his Democratic Party after public broadcaster NHK reported that 57 of its lawmakers failed to back the bill. Cabinet members seen are (top R to bottom) Deputy Prime Minister, who is also in charge of Social Security and Tax Reform, Katsuya Okada, International Affairs and Communications Minister Tatsuo Kawabata, Foreign Minister Koichiro Gemba and Economy, Trade and Industry Minister Yukio Edano. REUTERS/Toru Hanai (JAPAN - Tags: BUSINESS POLITICS) 

Japan's Prime Minister Yoshihiko Noda (2nd R) and Vice Prime Minister Katsuya Okada (2nd L) are guided to their positions as they prepare to pose for a photo after their first cabinet meeting at the premier's official residence in Tokyo June 4, 2012. Japanese Prime Minister Yoshihiko Noda replaced five cabinet ministers on Monday hoping to smooth the way to a deal with the opposition on doubling sales tax in spite of a rift in the ruling party over the plan. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's Deputy Prime Minister Katsuya Okada speaks at an interview with Reuters in Tokyo February 23, 2012. Okada said on Thursday that the nation's economy is still threatened by a strong yen and he wants the currency to weaken further. To match Interview JAPAN-ECONOMY/OKADA
REUTERS/Kim Kyung-Hoon (JAPAN - Tags: POLITICS HEADSHOT BUSINESS) 

Japan's Deputy Prime Minister Katsuya Okada speaks at an interview with Reuters in Tokyo February 23, 2012. Okada said on Thursday that the nation's economy is still threatened by a strong yen and he wants the currency to weaken further. To match Interview JAPAN-ECONOMY/OKADA
REUTERS/Kim Kyung-Hoon (JAPAN - Tags: POLITICS BUSINESS) 

Japan's Deputy Prime Minister Katsuya Okada speaks at an interview with Reuters in Tokyo February 23, 2012. Okada said on Thursday that the nation's economy is still threatened by a strong yen and he wants the currency to weaken further. To match Interview JAPAN-ECONOMY/OKADA
REUTERS/Kim Kyung-Hoon (JAPAN - Tags: POLITICS BUSINESS) 

Japan's Deputy Prime Minister Katsuya Okada speaks at an interview with Reuters in Tokyo February 23, 2012. Okada said on Thursday that the nation's economy is still threatened by a strong yen and he wants the currency to weaken further. To match Interview JAPAN-ECONOMY/OKADA REUTERS/Kim Kyung-Hoon (JAPAN - Tags: POLITICS BUSINESS HEADSHOT) 

Japan's Prime Minister Yoshihiko Noda speaks during a news conference at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's newly-appointed Vice Prime Minister Katsuya Okada speaks during a news conference at the Prime Minister's official residence in Tokyo January 13, 2012. Japan's Prime Minister Yoshihiko Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS /Toru Hanai (JAPAN - Tags: POLITICS HEADSHOT) 

Japan's newly-appointed Vice Prime Minister Katsuya Okada speaks during a news conference at the Prime Minister's official residence in Tokyo January 13, 2012. Japan's Prime Minister Yoshihiko Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS HEADSHOT) 

Japan's Prime Minister Yoshihiko Noda speaks during a news conference at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's Prime Minister Yoshihiko Noda speaks during a news conference at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS HEADSHOT) 

Japan's Prime Minister Yoshihiko Noda (2nd R) walks past newly-appointed Vice Prime Minister Katsuya Okada (L) and his cabinet members as he attends a news conference at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's Prime Minister Yoshihiko Noda (C) walks away in front of newly-appointed Vice Prime Minister Katsuya Okada (front 2nd R) after posing for a group photo with other cabinet members at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's Prime Minister Yoshihiko Noda walks at the prime minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS HEADSHOT) 

Japan's Prime Minister Yoshihiko Noda (C), newly-appointed Vice Prime Minister Katsuya Okada (R) and his cabinet members prepare to pose for a photo at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's Prime Minister Yoshihiko Noda (front C), newly-appointed Vice Prime Minister Katsuya Okada (front 2nd R) and cabinet members prepare to pose for a photo at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's Prime Minister Yoshihiko Noda walks at the Prime Minister's official residence in Tokyo January 13, 2012. Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's newly-appointed Vice Prime Minister Katsuya Okada is silhouetted as he uses a mobile phone at the prime minister's official residence in Tokyo January 13, 2012. Prime Minister Yoshihiko Noda appointed fiscal hawk Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's newly-appointed Vice Prime Minister Katsuya Okada, uses a mobile phone as he walks at the prime minister's official residence in Tokyo January 13, 2012. Prime Minister Yoshihiko Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's newly-appointed Vice Prime Minister Katsuya Okada arrives at the prime minister's official residence in Tokyo January 13, 2012. Prime Minister Yoshihiko Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN - Tags: POLITICS) 

Japan's newly-appointed Vice Prime Minister Katsuya Okada walks at the prime minister's official residence in Tokyo January 13, 2012. Prime Minister Yoshihiko Noda appointed fiscal hawk Katsuya Okada as his deputy in charge of tax and social security reform on Friday, signalling determination to forge ahead with sales tax increases despite a deadlocked parliament. REUTERS/Toru Hanai (JAPAN) 

Japan's new Prime Minister Yoshihiko Noda arrives at the premier's official residence in Tokyo September 2, 2011. Incoming Noda is seeking a new finance minister for his cabinet after his first choice for the key job, Katsuya Okada, turned it down, public broadcaster NHK reported on Friday. REUTERS/Yuriko Nakao (JAPAN - Tags: POLITICS) 

Japan's new Prime Minister Yoshihiko Noda arrives at the premier's official residence in Tokyo September 2, 2011. Incoming Noda is seeking a new finance minister for his cabinet after his first choice for the key job, Katsuya Okada, turned it down, public broadcaster NHK reported on Friday. REUTERS/Yuriko Nakao (JAPAN - Tags: POLITICS) 

Japan's new Prime Minister Yoshihiko Noda (L) arrives at the premier's official residence in Tokyo September 2, 2011. Incoming Noda is seeking a new finance minister for his cabinet after his first choice for the key job, Katsuya Okada, turned it down, public broadcaster NHK reported on Friday. REUTERS/Yuriko Nakao (JAPAN - Tags: POLITICS) 

Japan's new Prime Minister Yoshihiko Noda arrives at the premier's official residence in Tokyo September 2, 2011. Incoming Noda is seeking a new finance minister for his cabinet after his first choice for the key job, Katsuya Okada, turned it down, public broadcaster NHK reported on Friday. REUTERS/Yuriko Nakao (JAPAN - Tags: POLITICS HEADSHOT) 

Japan's new Prime Minister Yoshihiko Noda arrives at the premier's official residence in Tokyo September 2, 2011. Incoming Noda is seeking a new finance minister for his cabinet after his first choice for the key job, Katsuya Okada, turned it down, public broadcaster NHK reported on Friday. REUTERS/Yuriko Nakao (JAPAN - Tags: POLITICS HEADSHOT) 

Japan's new Prime Minister Yoshihiko Noda bows as he arrives at the premier's official residence in Tokyo September 2, 2011. Incoming Noda is seeking a new finance minister for his cabinet after his first choice for the key job, Katsuya Okada, turned it down, public broadcaster NHK reported on Friday. REUTERS/Yuriko Nakao (JAPAN - Tags: POLITICS)