Like two feuding branches of a family that fell out badly a few generations ago, but which now sense that the time has long passed to bury the hatchet, Japan and China are again straining to be friends. Relations between Asia's two giants blow hot and cold, whatever Hu Jintao, China's President, might say about Sino-Japanese ties now entering an “everlasting warm spring”.

The latest test of this new diplomatic warmth came yesterday afternoon when the first Japanese warship to visit China since the Second World War docked in a southern Chinese port, laden with relief supplies for victims of last month's Sichuan earthquake. And also a band, which will perform “friendship” concerts during the destroyer's five-day stay (see page 33).

The symbolism is not lost on the authorities in Beijing, who launched this latest round of diplomatic ping-pong by sending a Chinese missile destroyer to visit Japan in November - the first Chinese ship to do so since 1891. But nor is it lost on the many Chinese who have long memories and short tempers when it comes to Japan. The Rape of Nanking remains raw to many Chinese, and the wound has been salted regularly by Japanese prime ministers who have made the annual pilgrimage to the Yasukuni shrine in Tokyo that honours Japan's most notorious war criminals.

It was such sensitivities that scuppered a plan last month for Japanese soldiers to set foot once again on Chinese soil, at China's invitation, to airlift tents and relief supplies to earthquake victims. Fears of public anger persuaded Japan to switch the cargo to chartered flights instead.

But, it seems, second time lucky. Maybe that everlasting warm spring has finally sprung.