The people of Japan should strive to properly understand their country's history when dealing with the rest of the world, Emperor Akihito has said.
Emperor Akihito appeared three times at his balcony on Friday
In a speech to mark his 72nd birthday, he said he hoped "knowledge about past facts will continue to be passed down in a proper manner."
Japan continues to struggle with the legacy of its past, and the issue often creates tension with its neighbours.
Akihito also spoke of the vital role of women in the imperial household.
In October a government panel recommended allowing female succession to avoid a potential crisis - no boys have been born into the imperial family for 40 years.
Akihito did not specifically comment on the proposed changes, but said: "The female members of the imperial household must have played major roles both tangible and intangible until now."
Greeting the crowds
Emperor Akihito appeared at the balcony of his palace on Friday morning, to greet the estimated 14,000 people who had come to celebrate his birthday.
His wife Empress Michiko and other members of the imperial household also greeted the crowds.
Akihito's comments to mark his birthday were actually made on Thursday, but a translation was released on Friday.
He said that in their dealings with other countries, it was important for the Japanese to remember that "there were rarely peaceful times for Japan" between 1927 to 1945.
Ties between China and Japan have deteriorated rapidly in recent years, in part due to Japan's attitude to its colonial and wartime history.
China cancelled a regional summit with Japan earlier this month in protest at continuing visits by the Japanese prime minister, Junichiro Koizumi, to a controversial war shrine.
There were also a number of attacks against Japanese buildings in China earlier this year, as Chinese crowds staged angry protests over Japanese school textbooks which they said misrepresented history.
The two countries still have strained relations.
On Thursday, Japan's Foreign Minister Taro Aso said China's military build-up was starting to be "a considerable threat" - a statement which a Chinese spokesman dismissed as irresponsible "rhetoric".
South Korea has also repeatedly accused Japan of not atoning for wartime abuses.