MORE ISLAND DRAMA: The fervor of China’s anti-Japan demonstrations and protests earlier this week has definitely calmed down but Fast Retailing’s Uniqlo chain is still feeling the heat of the two countries’ ongoing diplomatic dispute- on its home turf of Japan. Fast Retailing chairman, president and chief executive Tadashi Yanai has even warned of a potential boycott.

As reported, the citizens of several Chinese cities took to the streets over the past several days, attacking Japanese-run retailers and businesses and overturning Japanese cars. A recent flare-up over a longstanding controversy about the ownership of a small chain of uninhabited islands prompted the violence. (Japan controls the islands but both countries claim sovereignty over them.)

Last Saturday, the manager of Uniqlo’s Shanghai store posted a sign in the window stating “the Senkaku Islands belong to China,” at the request of local police to diffuse the tense situation, according to a Fast Retailing spokesman. He said the sign was on display for only 40 minutes before it was removed.

“This incident did not take place under company instruction, nor has a similar incident taken place at any of our other stores,” Fast Retailing said Friday in a release. “Since September 18, several cases have been reported where similar signs have been posted at our temporarily closed stores in China. However, these signs have all been posted by third parties from outside the stores, and we have taken them down as soon as we find them.”

But in the meantime, Japanese media have picked up on the story and Japanese consumers are reacting to the incident.

Fast Retailing said it has received 1,431 emails and phone calls through Wednesday, with some customers voicing feelings of betrayal and others vowing never to shop at the fast-fashion retailer’s stores again. The Nikkei newspaper quoted Yanai as saying that “a misunderstanding could lead to calls for a boycott” of the company’s products in Japan.

Fast Retailing said its policy is to not take a stance on political issues, and it said it will take measures to ensure similar incidents do not occur in the future.

Uniqlo currently operates 145 stores in China. It shuttered 60 of its stores on Tuesday as a protective measure during the protests. Fast Retailing said Friday that five of its stores were still closed as of Thursday.