Japan's Emperor Akihito (R) and Empress Michiko board a special flight for their visit to the Philippines at Tokyo's Haneda Airport, Japan, January 26, 2016. REUTERS/Toru Hanai

Japan's Emperor Akihito (L) and Empress Michiko (2nd L) talk with Crown Prince Naruhito (C), Crown Princess Masako (2nd R) and Prince Akishino before boarding a special flight for their visit to the Philippines at Tokyo's Haneda Airport, Japan, January 26, 2016. REUTERS/Toru Hanai

Japan's Emperor Akihito (2nd L) and Empress Michiko (R) walk in front of Crown Prince Naruhito (L) and Crown Princess Masako as they board a special flight for a visit to the Philippines, at Tokyo's Haneda Airport in Japan January 26, 2016.REUTERS/Toru Hanai

Japan's Emperor Akihito (L) and Empress Michiko walk as they board a special flight for their visit to the Philippines at Tokyo's Haneda Airport, Japan, January 26, 2016. REUTERS/Toru Hanai

Japan's Emperor Akihito (L) and Empress Michiko bow as they board a special flight for their visit to the Philippines, at Tokyo's Haneda Airport in Japan January 26, 2016. REUTERS/Toru Hanai

Japan's Emperor Akihito (L) and Empress Michiko board a special flight for their visit to the Philippines, at Tokyo's Haneda Airport in Japan January 26, 2016. REUTERS/Toru Hanai

Japan's Emperor Akihito (L) and Empress Michiko board a special flight for their visit to the Philippines, at Tokyo's Haneda Airport in Japan January 26, 2016. REUTERS/Toru Hanai

Japan's Emperor Akihito (3rd L), flanked by other members of the royal family, waves to well-wishers who gathered to celebrate his 82nd birthday in Tokyo, Japan, December 23, 2015. REUTERS/Thomas Peter 

Japan's Crown Prince Naruhito (L-R), Emperor Akihito, Crown Princess Masako, Empress Michiko and Prince Akishino stand in front of well-wishers who gathered to celebrate the monarch's 82nd birthday in Tokyo, Japan, December 23, 2015. REUTERS/Thomas Peter 

Japan's Emperor Akihito's waves to well-wishers who gathered at the Imperial Palace to mark his 82nd birthday in Tokyo, Japan, December 23, 2015. REUTERS/Thomas Peter 

Japan's Emperor Akihito (L) and Empress Michiko wave to well-wishers who gathered at the Imperial Palace to mark his 82nd birthday in Tokyo, Japan, December 23, 2015. REUTERS/Thomas Peter 

Japan's Emperor Akihito's waves to well-wishers who gathered at the Imperial Palace to mark his 82nd birthday in Tokyo, Japan, December 23, 2015. REUTERS/Thomas Peter 

Japan's Emperor Akihito's waves to well-wishers who gathered at the Imperial Palace to mark his 82nd birthday in Tokyo, Japan, December 23, 2015. REUTERS/Thomas Peter 

Japan's Emperor Akihito (L) and Empress Michiko are pictured at the Imperial Palace in Tokyo, in this handout picture taken December 9, 2015 and released by the Imperial Household Agency of Japan. Empreror Akihito celebrated his 82nd birthday on December 23. REUTERS/Imperial Household Agency of Japan/Handout via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS 

Japan's Crown Prince Naruhito (3rd L) and Crown Princess Masako (4th L) greet guests with Prince Akishino (4th R), Princess Kiko (2nd R) and their daughter Princess Mako (R), during the annual autumn garden party hosted by Emperor Akihito and Empress Michiko (not in picture) at the Akasaka Palace imperial garden in Tokyo November 12, 2015. Crown Princess Masako took part in the garden party for the first time since the autumn party in 2003. REUTERS/Toru Yamanaka/Pool

Japan's Emperor Akihito (L) and Empress Michiko arrive at a memorial service ceremony marking the 70th anniversary of Japan's surrender in World War Two at Budokan Hall in Tokyo August 15, 2015. Emperor Akihito marked the 70th anniversary of the end of World War Two with an expression of "deep remorse" over the conflict on Saturday, a departure from his annual script which could be seen as a subtle rebuke of conservative Prime Minister Shinzo Abe. REUTERS/Toru Hanai

Japan's Emperor Akihito (R) and Empress Michiko attend a memorial service ceremony marking the 70th anniversary of Japan's surrender in World War Two at Budokan Hall in Tokyo August 15, 2015. Japanese Emperor Akihito marked the 70th anniversary of the end of World War Two with an expression of "deep remorse" over the conflict on Saturday, a departure from his annual script which could be seen as a subtle rebuke of conservative Prime Minister Shinzo Abe. REUTERS/Toru Hanai

Japan's Emperor Akihito (R) and Empress Michiko attend a memorial service ceremony marking the 70th anniversary of Japan's surrender in World War Two at Budokan Hall in Tokyo August 15, 2015. Japanese Emperor Akihito marked the 70th anniversary of the end of World War Two with an expression of "deep remorse" over the conflict on Saturday, a departure from his annual script which could be seen as a subtle rebuke of conservative Prime Minister Shinzo Abe. REUTERS/Toru Hanai

Japan's Emperor Akihito (L) delivers a speech next to Empress Michiko after they offer a moment of silence to the war dead during a memorial service ceremony marking the 70th anniversary of Japan's surrender in World War Two at Budokan Hall in Tokyo August 15, 2015. Japanese Emperor Akihito marked the 70th anniversary of the end of World War Two with an expression of "deep remorse" over the conflict on Saturday, a departure from his annual script which could be seen as a subtle rebuke of conservative Prime Minister Shinzo Abe. REUTERS/Toru Hanai 

Japan's Emperor Akihito and Empress Michiko (R) bow at an altar as they offer a moment of silence to war dead during a memorial service ceremony marking the 70th anniversary of Japan's surrender in World War Two, at Budokan Hall in Tokyo August 15, 2015. Japanese Emperor Akihito marked the 70th anniversary of the end of World War Two with an expression of "deep remorse" over the conflict on Saturday, a departure from his annual script which could be seen as a subtle rebuke of conservative Prime Minister Abe. REUTERS/Toru Hanai 

Japan's Emperor Akihito and Empress Michiko (R) bow at an altar as they offer a moment of silence to war dead during a memorial service ceremony marking the 70th anniversary of Japan's surrender in World War Two, at Budokan Hall in Tokyo August 15, 2015. Japanese Emperor Akihito marked the 70th anniversary of the end of World War Two with an expression of "deep remorse" over the conflict on Saturday, a departure from his annual script which could be seen as a subtle rebuke of conservative Prime Minister Abe. REUTERS/Toru Hanai

This photo provided by the Imperial Household Agency of Japan on August 1, 2015, shows two of the original recording of late emperor Hirohito's war-ending speech in Tokyo. REUTERS/Imperial Household Agency of Japan/Handout via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. 

Honduras' President Juan Orlando Hernandez (3rd L) talks with Japan's Emperor Akihito (L) as Empress Michiko talks with the first lady of Honduras, Ana Garcia de Hernandez (3rd R) during a meeting at the Imperial Palace in Tokyo July 23, 2015, in this handout photo taken and released by the Imperial Household Agency of Japan. REUTERS/Imperial Household Agency of Japan/Handout via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. 

Honduras' President Juan Orlando Hernandez (L) is greeted by Japan's Emperor Akihito (2nd L) as Empress Michiko (R) speaks with the first lady of Honduras, Ana Garcia de Hernandez after a meeting at the Imperial Palace in Tokyo July 23, 2015, in this handout photo taken and released by the Imperial Household Agency of Japan. REUTERS/Imperial Household Agency of Japan/Handout via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. 

Honduras' President Juan Orlando Hernandez (L) and Japan's Emperor Akihito (2nd L) walk in for a meeting at the Imperial Palace in Tokyo July 23, 2015, in this handout photo taken and released by the Imperial Household Agency of Japan. REUTERS/Imperial Household Agency of Japan/Handout via Reuters ATTENTION EDITORS - THIS PICTURE WAS PROVIDED BY A THIRD PARTY. REUTERS IS UNABLE TO INDEPENDENTLY VERIFY THE AUTHENTICITY, CONTENT, LOCATION OR DATE OF THIS IMAGE. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS PICTURE IS DISTRIBUTED EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. 

Japan's Emperor Akihito (C) and Empress Michiko (front L) get out of their car, as they board a special flight for a visit to Palau, at Haneda international airport in Tokyo April 8, 2015. Emperor Akihito heads on Wednesday for the island nation of Palau where he will visit a World War Two battlefield, the latest journey in his efforts to soothe the wounds of a conflict that haunts Asia 70 years after its end. REUTERS/Issei Kato TPX IMAGES OF THE DAY

Masao Horie, survivor of a doomed campaign in New Guinea, speaks during an interview with Reuters at his house in Tokyo March 26, 2015. Japanese Emperor Akihito heads on April 8, 2015 for the island nation of Palau where he will visit a World War Two battlefield, the latest journey in his efforts to soothe the wounds of a conflict that still haunts Asia 70 years after its end. Some 10,000 Japanese defenders, fighting in the name of Akihito's father, Emperor Hirohito, died in a two-month battle in late 1944 on Palau's tiny Peleliu island along with about 1,600 American troops. Unaware Japan had surrendered on Aug. 15, 1945, 34 Japanese soldiers hid in the jungle until April 1947. Picture taken March 26, 2015. REUTERS/Yuya Shino 

Masao Horie, survivor of a doomed campaign in New Guinea, points out a pictures of him at his departure to New Guinea at age of 28 in 1943 during an interview with Reuters at his house in Tokyo March 26, 2015. Japanese Emperor Akihito heads on April 8, 2015 for the island nation of Palau where he will visit a World War Two battlefield, the latest journey in his efforts to soothe the wounds of a conflict that still haunts Asia 70 years after its end. Some 10,000 Japanese defenders, fighting in the name of Akihito's father, Emperor Hirohito, died in a two-month battle in late 1944 on Palau's tiny Peleliu island along with about 1,600 American troops. Unaware Japan had surrendered on Aug. 15, 1945, 34 Japanese soldiers hid in the jungle until April 1947. Picture taken March 26, 2015. REUTERS/Yuya Shino 

Masao Horie, survivor of a doomed campaign in New Guinea, speaks during an interview with Reuters at his house in Tokyo March 26, 2015. Japanese Emperor Akihito heads on April 8, 2015 for the island nation of Palau where he will visit a World War Two battlefield, the latest journey in his efforts to soothe the wounds of a conflict that still haunts Asia 70 years after its end. Some 10,000 Japanese defenders, fighting in the name of Akihito's father, Emperor Hirohito, died in a two-month battle in late 1944 on Palau's tiny Peleliu island along with about 1,600 American troops. Unaware Japan had surrendered on Aug. 15, 1945, 34 Japanese soldiers hid in the jungle until April 1947. Picture taken March 26, 2015. REUTERS/Yuya Shino 

Masao Horie, survivor of a doomed campaign in New Guinea, shows his poem about Japan's defeat in WWII when he wrote on the day the war ended during an interview with Reuters at his house in Tokyo March 26, 2015. Japanese Emperor Akihito heads on April 8, 2015 for the island nation of Palau where he will visit a World War Two battlefield, the latest journey in his efforts to soothe the wounds of a conflict that still haunts Asia 70 years after its end. Some 10,000 Japanese defenders, fighting in the name of Akihito's father, Emperor Hirohito, died in a two-month battle in late 1944 on Palau's tiny Peleliu island along with about 1,600 American troops. Unaware Japan had surrendered on Aug. 15, 1945, 34 Japanese soldiers hid in the jungle until April 1947. The Chinese characters (R) in the note reads in Japanese "Defeat". Picture taken March 26, 2015. REUTERS/Yuya Shino 

Masao Horie, survivor of a doomed campaign in New Guinea, speaks during an interview with Reuters at his house in Tokyo March 26, 2015. Japanese Emperor Akihito heads on April 8, 2015 for the island nation of Palau where he will visit a World War Two battlefield, the latest journey in his efforts to soothe the wounds of a conflict that still haunts Asia 70 years after its end. Some 10,000 Japanese defenders, fighting in the name of Akihito's father, Emperor Hirohito, died in a two-month battle in late 1944 on Palau's tiny Peleliu island along with about 1,600 American troops. Unaware Japan had surrendered on Aug. 15, 1945, 34 Japanese soldiers hid in the jungle until April 1947. Picture taken March 26, 2015. REUTERS/Yuya Shino 

Masao Horie, survivor of a doomed campaign in New Guinea, speaks during an interview with Reuters at his house in Tokyo March 26, 2015. Japanese Emperor Akihito heads on April 8, 2015 for the island nation of Palau where he will visit a World War Two battlefield, the latest journey in his efforts to soothe the wounds of a conflict that still haunts Asia 70 years after its end. Some 10,000 Japanese defenders, fighting in the name of Akihito's father, Emperor Hirohito, died in a two-month battle in late 1944 on Palau's tiny Peleliu island along with about 1,600 American troops. Unaware Japan had surrendered on Aug. 15, 1945, 34 Japanese soldiers hid in the jungle until April 1947. Picture taken March 26, 2015. REUTERS/Yuya Shino 

U.S. first lady Michelle Obama (L) gets caught a bump before shaking hand with Emperor Akihito (C) and Empress Michiko at the Imperial Palace in Tokyo March 19, 2015. Michelle Obama flew in to Japan on Wednesday for a three-day visit as part of the Let Girls Learn international girls education initiative. REUTERS/Eugene Hoshiko/Pool TPX IMAGES OF THE DAY 

Champagne is poured for U.S. President Barack Obama (2nd L) and Japan's Emperor Akihito (R) during the Japan State Dinner at the Imperial Palace in Tokyo, April 24, 2014. REUTERS/Larry Downing (JAPAN - Tags: POLITICS ROYALS ENTERTAINMENT TPX IMAGES OF THE DAY) 

Japan's Crown Prince Naruhito (L-R), Emperor Akihito, Crown Princess Masako and Empress Michiko stand in front of well-wishers who gathered to celebrate the monarch's 80th birthday at the Imperial Palace in Tokyo December 23, 2013. REUTERS/Yuya Shino (JAPAN - Tags: ROYALS) 

Cast members Tommy Lee Jones (3rd L), Matthew Fox (3rd R), Kaori Momoi (L), Toshiyuki Nishida (2nd L), Eriko Hatsune (2nd R) and director Peter Webber pose during a photo session to promote their movie "Emperor" in the room at the U.S. ambassador's residence where U.S. General Douglas MacArthur met Japanese Emperor Hirohito on September 27, 1945 following Japan's surrender at the end of World War Two, in Tokyo July 18, 2013. The movie will go on public release in Japan from July 27, 2013. REUTERS/Issei Kato (JAPAN - Tags: ENTERTAINMENT) 

Cast member Matthew Fox prepares for a photo session to promote the movie "Emperor" in the room at the U.S. ambassador's residence where U.S. General Douglas MacArthur met Japanese Emperor Hirohito on September 27, 1945 following Japan's surrender at the end of World War Two, in Tokyo July 18, 2013. The movie will go on public release in Japan from July 27, 2013. REUTERS/Issei Kato (JAPAN - Tags: ENTERTAINMENT) 

Cast members Tommy Lee Jones (3rd L), Matthew Fox (3rd R), Kaori Momoi (L), Toshiyuki Nishida (2nd L), Eriko Hatsune (2nd R) and director Peter Webber pose during a photo session to promote their movie "Emperor", in the room at the U.S. ambassador's residence where U.S. General Douglas MacArthur met Japanese Emperor Hirohito on September 27, 1945 following Japan's surrender at the end of World War Two, in Tokyo July 18, 2013. The movie will go on public release in Japan from July 27, 2013. REUTERS/Issei Kato (JAPAN - Tags: ENTERTAINMENT) 

A declaration message by the late Japanese Emperor Hirohito is seen in the first page of the replica of an official original copy of the Constitution of Japan, during a photo opportunity at National Archives of Japan in Tokyo May 21, 2013. Japan's Prime Minister Shinzo Abe makes no secret of wanting to revise Japan's constitution, which was drafted by the United States after World War Two, to formalise the country's right to have a military - but critics say his plans go deeper and could return Japan to its socially conservative, authoritarian past. Abe, 58, returned to office in December for a second term as prime minister and is enjoying sky-high support on the back of his "Abenomics" recipe for reviving the economy through hyper-easy monetary policy, big spending and structural reform. Now he is seeking to lower the hurdle for revising the constitution as a prelude to an historic change to its pacifist Article 9 - which, if strictly read, bans any military. REUTERS/Issei Kato (JAPAN - Tags: POLITICS CONFLICT) 

The signature and seal of the late Japanese Emperor Hirohito are seen on the replica of an official original copy of the Constitution of Japan, during a photo opportunity at National Archives of Japan in Tokyo May 21, 2013. Japan's Prime Minister Shinzo Abe makes no secret of wanting to revise Japan's constitution, which was drafted by the United States after World War Two, to formalise the country's right to have a military - but critics say his plans go deeper and could return Japan to its socially conservative, authoritarian past. Abe, 58, returned to office in December for a second term as prime minister and is enjoying sky-high support on the back of his "Abenomics" recipe for reviving the economy through hyper-easy monetary policy, big spending and structural reform. Now he is seeking to lower the hurdle for revising the constitution as a prelude to an historic change to its pacifist Article 9 - which, if strictly read, bans any military. REUTERS/Issei Kato (JAPAN - Tags: POLITICS CONFLICT) 

The signature and seal of the late Japanese Emperor Hirohito are seen on the replica of an official original copy of the Constitution of Japan, during a photo opportunity at National Archives of Japan in Tokyo May 21, 2013. Japan's Prime Minister Shinzo Abe makes no secret of wanting to revise Japan's constitution, which was drafted by the United States after World War Two, to formalise the country's right to have a military - but critics say his plans go deeper and could return Japan to its socially conservative, authoritarian past. Abe, 58, returned to office in December for a second term as prime minister and is enjoying sky-high support on the back of his "Abenomics" recipe for reviving the economy through hyper-easy monetary policy, big spending and structural reform. Now he is seeking to lower the hurdle for revising the constitution as a prelude to an historic change to its pacifist Article 9 - which, if strictly read, bans any military. REUTERS/Issei Kato (JAPAN - Tags: POLITICS CONFLICT) 

Japanese lawmakers raise their hands as they shout traditional "Banzai (long life)" cheers to Emperor Akihito (L) and Empress Michiko during a ceremony to commemorate the anniversary of Japan's restoration of sovereignty and return into the international community, in Tokyo April 28, 2013. Prime Minister Shinzo Abe's government held a ceremony on Sunday to mark the restoration of Japan's sovereignty seven years after defeat in World War Two, a sign of his drive to repair what conservatives consider dented national pride. REUTERS/Itsuo Inouye/Pool (JAPAN - Tags: ANNIVERSARY ENTERTAINMENT POLITICS ROYALS) 

Japan's Emperor Akihito (R) and Empress Michiko leave after praying at the altar of late Prince Tomohito, a cousin of the Emperor, in Tokyo June 19, 2012. Tomohito, who was sixth in line to the Chrysanthemum Throne, died of cancer at 66 on June 6. REUTERS/Itsuo Inouye/Pool (JAPAN - Tags: OBITUARY ROYALS TPX IMAGES OF THE DAY) 

Kuwait's Emir Sheikh Sabah al-Ahmad Al-Sabah (2nd L) greets Japanese Empress Michiko (R) and Emperor Akihito (2nd R) while receiving a farewell call at the Akasaka state guesthouse in Tokyo March 23, 2012. REUTERS/Toshifumi Kitamura/Pool (JAPAN - Tags: POLITICS ROYALS) 

Japan's Emperor Akihito and Empress Michiko bow in front of relatives of people who died in World War Two during a memorial ceremony marking the 66th anniversary of Japan's surrender in the war at Budokan Hall in Tokyo August 15, 2011. REUTERS/Yuriko Nakao (JAPAN - Tags: ANNIVERSARY DISASTER POLITICS ROYALS) 

Japan's Emperor Akihito (R) and Empress Michiko bow as they offer prayers before an altar for those who died in World War Two during a memorial service ceremony marking the 66th anniversary of Japan's surrender in the war at Budokan Hall in Tokyo August 15, 2011. REUTERS/Yuriko Nakao (JAPAN - Tags: ANNIVERSARY DISASTER POLITICS ROYALS) 

Japan's Emperor Akihito (R) talks with evacuees from the March 11 earthquake and tsunami, at Tokyo Budoh-kan, currently an evacuation shelter, in Tokyo March 30, 2011. The Emperor and Empress Michiko visited the shelter on Wednesday to encourage the some 300 evacuees, mainly from Fukushima Prefecture. Japan's trade ministry ordered nuclear power plant operators to immediately start implementing new safety measures on Wednesday in light of the crisis at the Fukushima plant, which it said was due to a higher tsunami than expected after the March 11 earthquake. REUTERS/Issei Kato (JAPAN - Tags: DISASTER POLITICS ROYALS ENVIRONMENT) 

Japan's Emperor Akihito (L) and Empress Michiko (2nd L) talk with evacuees from the March 11 earthquake and tsunami, at Tokyo Budoh-kan, currently an evacuation shelter, in Tokyo March 30, 2011. The Emperor and Empress visited the shelter on Wednesday to encourage the some 300 evacuees, mainly from Fukushima Prefecture. Japan's trade ministry ordered nuclear power plant operators to immediately start implementing new safety measures on Wednesday in light of the crisis at the Fukushima plant, which it said was due to a higher tsunami than expected after the March 11 earthquake. REUTERS/Issei Kato (JAPAN - Tags: DISASTER POLITICS ROYALS ENVIRONMENT) 

Japan's Emperor Akihito is seen through banners of right-wing groups as he makes a speech to well-wishers at an event to celebrate his 76th birthday at the Imperial Palace in Tokyo December 23, 2009. The banner reads: "Emperor". REUTERS/Kim Kyung-Hoon (JAPAN - Tags: ROYALS IMAGES OF THE DAY) 

Japan's Emperor Akihito (3rd L) waves to well-wishers with Empress Michiko (3rd R), Crown Prince Naruhito (2nd L) and Crown Princess Masako (L) and Prince Akishino (2nd R) and his wife Princess Kiko as they celebrate the monarch's 76th birthday at the Imperial Palace in Tokyo December 23, 2009. REUTERS/Kim Kyung-Hoon (JAPAN - Tags: ROYALS) 

Japan's Emperor Akihito (3rd R) and the royal family members, (R-L) Empress Michiko, Crown Princess Masako, Crown Prince Naruhito, Prince Akishino, Princess Kako, Princess Kiko and Prince Hisahito, ride on a solar-powered small locomotive as they visit Kodomonokuni, or Children's Land, marking the 50th anniversary of the royal marriage of Emperor Akihito and Empress Michiko, in Yokohama near Tokyo, December 19, 2009. The natural park was founded in commemoration of the royal marriage in 1959. REUTERS/Shuji Kajiyama/Pool (JAPAN - Tags: ROYALS ANNIVERSARY) 

U.S. President Barack Obama is greeted by Japanese Emperor Akihito and Empress Michiko upon arrival at the Imperial Palace in Tokyo November 14, 2009. REUTERS/Jim Young (JAPAN POLITICS IMAGES OF THE DAY) 

Emperor Akihito (L) and Empress Michiko stand on a bridge on the Palace grounds during an event to celebrate the 20th anniversary of the Emperor's ascension to the throne in Tokyo November 12, 2009. Japanese Emperor Akihito, whose efforts to soothe Asia's bitter wartime memories have been central to his 20 years on the throne, said his biggest worry is that future generations in his country will forget the past. REUTERS/Franck Robichon/Pool (JAPAN ROYALS ANNIVERSARY IMAGES OF THE DAY) 

Emperor Akihito and Empress Michiko (R) attend an event to celebrate the 20th anniversary of the Emperor's ascension to the throne in Tokyo November 12, 2009. Japanese Emperor Akihito, whose efforts to soothe Asia's bitter wartime memories have been central to his 20 years on the throne, said his biggest worry is that future generations in his country will forget the past. REUTERS/Junji Kurokawa/Pool (JAPAN ROYALS ANNIVERSARY IMAGES OF THE DAY) 

A protester holds a cut-out of late Japan's Emperor Hirohito during a rally against celebrations the 20th anniversary of Emperor Akihito's ascension to the throne in Tokyo November 12, 2009. Emperor Akihito, whose efforts to soothe Asia's bitter wartime memories have been central to his 20 years on the throne, said his biggest worry is that future generations in his country will forget the past. REUTERS/Toru Hanai (JAPAN ANNIVERSARY POLITICS ROYALS) 

A protester holds a cut-out of late Japan's Emperor Hirohito during a rally against celebrations of the 20th anniversary of Emperor Akihito's ascension to the throne in Tokyo November 12, 2009. Emperor Akihito, whose efforts to soothe Asia's bitter wartime memories have been central to his 20 years on the throne, said his biggest worry is that future generations in his country will forget the past. REUTERS/Toru Hanai (JAPAN ANNIVERSARY POLITICS ROYALS IMAGES OF THE DAY)