TOKYO (AFP) - Britain's Prince William compared royal notes with Japan's imperial family on Friday in the tradition-laden Imperial Palace that dominates central Tokyo.
The young scion of the House of Windsor was welcomed by Emperor Akihito and Empress Michiko at the entrance of the imposing palace, which is cut off from the hustle and bustle of Tokyo by a large moat.
Akihito, whose family claims to be able to trace its imperial ancestry for thousands of years, looked frail next to the hearty former helicopter pilot, whose wife, Kate, is due to give birth to the couple's second child in April.
Pictures showed William, 32, shaking hands with the 81-year-old emperor, and Japanese media reported he had thanked the royal couple for an invitation that had brought him to Japan for the first time.
Speaking at a reception later in the day, William said he was "immensely honoured to have been received by Their Majesties".
William, who is also Duke of Cambridge, later met Crown Prince Naruhito at a separate palace for a tea ceremony. The latter lives a different, more cloistered existence than the jet-set lifestyles of William and his brother, Harry.
On the death of his father, Naruhito will inherit the Chrysanthemum Throne, a role that was largely stripped of its quasi-religious mystique by American occupiers after World War II.
William had spent the morning paying tribute to British and other soldiers who gave their lives during those hostilities over seven decades ago, laying a wreath at a Commonwealth War Cemetery in Yokohama, near Tokyo.
The cemetery is the resting place of 1,700 prisoners of war brought to Japan as forced labourers during Tokyo's ill-fated stomp through Asia, which ended in brutal atomic defeat in 1945.
MEMORIES OF DIANA
William became the latest in a line of distinguished British visitors to the cemetery, after former Prime Minister Margaret Thatcher, Queen Elizabeth, and his mother, the late Princess Diana.
William looked at pictures of his mother's visits - in 1990 and 1995 - and footage of her trip was replayed on Japanese television.
The Princess of Wales was immensely popular in Japan, her visits setting off so-called "Diana Fever" as tens of thousands flocked to meet her and as women sought to copy her carefully-coiffured hair and stylish dress-sense.
The young prince has something of that star power for many Japanese, who speak admiringly of his apparent warmth and ease with members of the public, although the absence of Kate and baby George has dimmed the appeal a little.
At a function to promote British industry in the afternoon, William looked slightly sheepish in a bright red "happi", a traditional Japanese housecoat, as he joined a Japanese astronaut to swing a wooden hammer and crack open a barrel of sake.
Following a reception at the British Embassy later Friday, William was due to set off on Saturday for Japan's northeast, the area that was devastated by a huge earthquake and tsunami in 2011.
More than 19,000 people died in the natural disaster, which also set off a nuclear emergency in Fukushima.
Tens of thousands of people were forced from their homes when three of the plant's reactors went into meltdown, spewing toxic radiation over a large area.
Many of those made homeless by the disaster remain displaced, and scientists say it could be decades before some areas are safe for human habitation again.
William is due to leave Japan on Sunday, bound for Beijing.