For the second time in less than two months, top political adviser Yu Zhengsheng met with a Japanese delegation, a move observers said emphasizes China's and Japan's efforts to mend ties that have recently experienced severe turbulence.

On Tuesday, Yu met with delegates from Japan's Social Democratic Party, the opposition party's first meeting with the Communist Party of China in Beijing in a decade.

Yu said the key to improving ties is to tackle tensions over both the Diaoyu Islands and Tokyo's acknowledgment of its past militarism with sincerity and actions that will lead to tangible results.