Just a few months ago, Chinese media denounced him as a counter-revolutionary.

Now, though, Doraemon – Japan’s beloved robot cat – is easing diplomatic tensions between Tokyo and Beijing, and breaking box-office records in the process.

The 3D animated film Stand By Me Doraemon brought in 30m yuan ($4.8m) in receipts on its opening day last Thursday, and repeated the feat the following day.

As parents and children packed out Chinese cinemas, receipts surged to 85m yuan and 88m yuan on Saturday and Sunday, surpassing the previous single-day record for animated movies, held by the US film Kung Fu Panda 2.

According to estimates, revenue from the Doraemon movie accounted for more than half of China’s total box-office revenues on Sunday, easily beating the US superhero blockbuster Avengers: Age of Ultron.

Doraemon, a chubby, perennially cheerful cat from the 22nd century, has charmed generations of Japanese fans with his teleportation powers, addiction to sweet bean pancakes and array of ingenious gadgets he uses to help his hapless schoolboy friend, Nobita.

The popularity of Stand By Me Doraemon reflects an easing in tensions between Japan and China over ownership of the Senkaku islands and interpretations of wartime history.

China’s leader, Xi Jinping, and his Japanese counterpart, Shinzo Abe, have met twice in the past six months, raising hopes of friendlier ties between the world’s second and third-biggest economies.

In recent remarks to a Japanese delegation of tourism and local government officials, Xi said he understood the importance of people-to-people exchanges, adding China was “ready to [negotiate] with the Japanese side to advance neighbourly friendship and cooperation”.

The Doraemon film, which will be shown at 5,500 screens across China over the coming month, is the first Japanese movie to go on general release in China since 2012, when Japan’s government bought the Senkaku islands from their private Japanese owners, effectively nationalising them.

The move sparked protests in several Chinese cities and sent bilateral ties to their lowest point in decades.

Doraemon’s attempts to win over China haven’t always been so well received, however.

Last October, a Chinese newspaper accused the blue cat of political subversion claiming his presence at an exhibition in the city of Chengdu was part of a plot to portray Japan in a kinder light as the countries traded verbal blows over the Senkakus and wartime history.

“Doraemon is a part of Japan’s efforts of exporting its national values and achieving its cultural strategy; this is an undisputed fact,” the Chengdu Daily said in an editorial. “Taking this to heart, we should be less blind and keep a cool head while kissing the cheeks of the chubby blue guy.”

In South Korea, where a ban on Japanese popular culture has been lifted in increments since the late 1990s, disputes over territory and the legacy of the second world war show little sign of easing.

A recent survey showed that mutual suspicion among the public remains high: 52% of Japanese polled said they had a negative view of South Koreans, while in South Korea, 73% said they felt similarly towards the Japanese.

Doraemon’s global popularity is such that in 2008 he was made an ambassador to promote Japanese popular culture overseas.

Having built a huge following in Japan since his comic book debut in 1969, he has become instantly recognisable throughout East Asia and, more recently, in the US.

The manga, created by Fujiko F Fujio, has sold well over 100m copies, making it one of the best-selling comics in the world, while the TV series has won over audiences in more than 30 countries.

Last summer, Doraemon made its US debut on the Disney XD satellite channel. In 2002, Time magazine named Doraemon one of its 22 Asian heroes.