China is apprehensive about Japan becoming more nationalistic after Prime Minister Shinzo Abe's ruling coalition scored a comfortable win in Sunday's Upper House election, giving the ruling bloc control of both Diet chambers for the first time in six years.

Chinese media and some experts expressed concern that the already strained bilateral relationship could unravel further and said they will be closely watching Abe in the days ahead for signs of whether he will moderate or toughen his already hard-line stance.

"It's none of China's business whether Japan has a stable government or not," said Shi Yinhong, a professor of international relations at Renmin University of China. "As long as Prime Minister Abe is in power, it will be difficult for the two countries to find ways in the near future to improve diplomatic ties."