Relations between the two countries have reached their lowest in decades after a row over disputed islands that has triggered anti-Japan protests in China but world number 17 Nishikori said he had no qualms about heading there.
"No, it should be fine," the 22-year-old, who reached the last eight of the Australian Open this year, said on Thursday.
"I don't want to get too much into it as my job is playing tennis and doing my best on the court. Anything can happen, but hopefully not."
China and Japan have a long-standing dispute over an uninhabited group of islands in the East China Sea - known as the Senkaku in Japan and Diaoyu in China.
The row escalated on Tuesday after two Japanese activists landed on one of the islands with Beijing describing the move as provocative. China complained to Tokyo and said it reserved the right to take further action.
The move came on the highly-charged anniversary of Japan's occupation of its giant neighbour in 1931.
The actions have led to a number of withdrawals of the Chinese and Japanese athletes from events hosted by their rivals with badminton and cycling among the sports affected.
Ishikawa was the latest victim when she was pulled out of a World Cup event in Huanghshi because Chinese organisers couldn't guarantee her safety with a wave of anti-Japan protests across the country.
"She is my friend too actually, it is a little bit sad because she loves ping pong and for me, I love playing tennis," Nishikori said of the London Olympic silver medallist.
"My job is playing tennis and (to) do well on the court and it's a little affecting sports too, little bit sad what is happening but hopefully (it would get resolved)."
Part of the reason that Nishikori is keen to return to Shanghai is that it was the scene of one of his career-best results.
The Florida-based 23-year-old reached the last four in Shanghai last year after beating France's Jo-Wilfried Tsonga along the way.
"I played well last year, the semis, the first time I made the semis of a Masters and that was my dream tournament and the people were very nice.
"My goal this year (is) to win a tournament especially in Asia with three tournaments coming from next week, so that is going to be very important for me to do well in this fall season."
U.S. Open champion Andy Murray was the man who ended Nishikori's run in China last year and the Japanese was full of praise for the Scot, who ended Britain's 76-year wait for a grand slam title.
"His tennis is a little bit same as mine, it is my goal to play like him. He has good defence but he is coming to the net more and more and much stronger now and hopefully I can learn a lot of things from him.
"I need to have more consistency on the court and be more aggressive on ground strokes and come into the net, and I have had so many injuries this year so I need to get more physically strong and try to be healthy."
The Japanese showed no sign of ill health as he braved the stifling heat in Singapore to team up with Marussia Formula One drivers Charles Pic and Timo Glock to play a tennis match in front of Marina Bay Sands near the street circuit for Sunday's race.