Xi Jinping, the man widely tipped to succeed Hu Jintao as China's president in 2012, dropped in on Japan's emperor this week. Though such visits are normally arranged months in advance, Beijing gave just a couple of days' notice, the equivalent in imperial-etiquette terms of loudly banging on your neighbour's door at 3am asking to borrow a cup of sugar.

A request by Yukio Hatoyama, Japan's freshly installed prime minister, that an audience be granted even at such short notice, was criticised by some in Japan, particularly on the right. They saw in it a willingness by the new left-of-centre government to kowtow to Beijing. Even the normally discreet head of the Imperial Household Agency, the stern and secretive body that controls the royal schedule, objected publicly that the emperor should not be used as a diplomatic tool.

These minor ructions obscured the more important fact: that the meeting took place at all. Mr Xi did not bow (cf Barack Obama). But he did coo, in no doubt entirely off-the-cuff remarks: "I hope my visit will contribute to the development of friendly co-operation between the two countries and boost friendship between the two peoples."