Aso and South Korean President Lee Myung-bak have both seen their support rates tumble as prospects for their export-dependent economies have dimmed. The two countries also have their eye on China's growing economic and diplomatic clout.
"It will be much more effective for South Korea to work with Japan in responding to China's potential (as an economic power)," said Lee Myon-woo of the Sejong Institute near Seoul. China is the top trading partner for both countries.
A possible drag on formal talks between the two leaders on Monday comes from lingering animosity in South Korea at Japan's 1910-1945 colonial rule over the Korean peninsula, with protesters already mounting small rallies in Seoul demanding compensation from Japan.
Source: FOCUS Information Agency