Nanjing is a haunted city, where the ghosts of the war with Japan have still yet to be laid to rest.

There are more than 20 memorials that honour the 300,000 men, woman and children that China says were slain in a six-week killing spree that Japan's invading army began 77 years ago today.

Tokyo still disputes that figure, insisting it was half that number. Either way, it still amounted to one of the worst wartime atrocities of the last century.

What happened here has come to define the problematic relationship between the two Asian superpowers.

It is a relationship marked by rivalry and bitterness.

China recently supplanted Japan as the world's second largest economy.

Beijing's increasingly assertive sovereignty adventures in the East China and South China Seas demonstrate that the balance of power could be shifting in other ways.

The view from Tokyo is that China uses its wartime past as a convenient stick with which to beat Japan whenever relations between the two are at a low ebb.

Relationship reset

At the beginning of the year that was all too apparent.

When China's government decided to demonstrate its displeasure with Tokyo, it up graded the Nanjing ceremony to make it a National Memorial Day.

But at the APEC summit in Beijing last month came a thaw in relations.

After an awkward handshake between President Xi Jinxing and Shinzo Abe, Japan's prime minister, who faces elections on Sunday, both men agreed to reset a strained relationship.

In his speech on Saturday, Xi reminded the world of what Japan did here.

"History will not change due to the changing times," he said.

"Facts will not disappear because of clever-tongue repudiation. The Nanjing Massacre, which was proven with ironclad evidence, cannot be tampered with. Any attempt to deny the fact of the Nanjing Massacre is unacceptable to history."

That much was predictable, but the conciliatory words at the end of his address were a surprise, a reflection perhaps of the diplomacy now under way to repair ties.

"We hold the memorial service for the victims of the Nanjing Massacre to evoke people's yearning for peace, and their determination to safeguard peace, rather than to perpetuate the hatred.

"Friendship between the Chinese and Japanese people should go on for coming generations, and the Chinese and Japanese people shall learn from the past, look to the future, and work together to contribute to peace."

Focus on the present

So this anniversary has been without the usual high-pitched, state-sanctioned anti-Japanese rhetoric.

In fact, the Chinese government seems more focused on the present than the past, as I discovered when interviewing a man outside the city's main war museum on Friday.

He had come from Jilin province, thousands of kilometres away.

His father had been a soldier with the nationalist forces defending the then capital when the Japanese attacked.

He told me he could not understand why Japan continued to deny that the massacre had ever happened.

Moments later police appeared, one blocking our camera. The man from Jilin was led away.

We later discovered he spent more than 18 hours in custody before finally being released on Saturday morning with a warning that he could not go anywhere near the memorial site.

His crime was to talk to a Western reporter about an event to which state television will devote Saturday's coverage.

The government is now keeping a lid on the anti-Japanese sentiment it was happily harnessing a few months ago.

Source: Al Jazeera