China’s loss to Japan on a popular game show devoted to mental athletics has left the country’s netizens atwitter and provoked some national soul-searching.

The battleground was the popular television show “Super Brain,” and the eventual winner a 9-year-old Japanese girl.

The series is a sort of weekly mental Olympics, pitting teams from around the world against China in a series of three brain-bending events.

In recent competitions, China has gone up against Germany and Britain, with contestants fighting over such questions of national honor as who can solve a Rubik’s cube the fastest.

Last Friday’s match against Japan — the country China loves to hate — was one of the most hotly anticipated, and widely watched, of the season.

For the last event in the triathlon, contestants were given mere seconds to find the answers to arithmetic problems that would take the average adult minutes — and a calculator — to solve.

When the dust settled, Japanese math prodigy Rinne Tsujikubo had demolished her Chinese competition, as well as fellow teammate Takeo Sasano.

Sasano, who is in his 30s, holds the Guinness World Record for mental addition: 15 three-digit numbers in 1.7 seconds.

The diminutive Tsujikubo played it cool throughout the contest, even after she mistakenly wrote one digit in a difficult problem.

That error allowed Team China to stay neck-and-neck for most of the competition, but in the last few minutes Tsujikubo completely blew the opposition away.

In the final round she multiplied two seven-digit numbers — and double-checked her work — before her competitors, or teammate, had seemingly even finished writing their answers.

The blistering speed with which she solved the problem left everyone, including the audience, dumbfounded and handed a win to Japan.

Xinhua, China’s official news agency, devoted a five-page write-up to the match, lavishing most of its attention on Tsujikubo’s mind-bending “mathleticism.”

What’s her secret? Studying the Japanese abacus, known as soroban, she told an interviewer before the show.

Abacus classes are a common, if not necessarily popular, after-school activity in Japan. After years of practice, devotees develop the ability to do sums on a mental calculator, solely based on visualization.

The skill is known as flash anzan (mental calculation) and is the centerpiece of an annual abacus competition.

Tsujikubo’s demonstration of the skill seems to have captivated Chinese viewers, who have watched the online version of the show almost 22 million times. Most were blown away by Tsujikubo’s superhuman arithmetic skills.

But inevitably, online comments showed signs of wounded nationalism. “Let’s fiercely trample Japan underfoot,” one commenter wrote.

Other viewers, however, had a more introspective take on Japan’s victory. Soroban, noted another commenter, were imported to Japan from China, where the tradition has largely died out.

“The island nation,” he wrote, referring to Japan, “defeated us with one of the best things left to us by our ancestors.” Perhaps, he said, “that’s worth reflecting on.”