Japan’s less-than-wholehearted remorse for its World War II-era atrocities has long been an unhealed wound in its relations with its neighbors. The bruise is throbbing anew with the approach of August 15, the 70th anniversary of the announcement of Japan’s surrender.

China’s ambassador to Tokyo revived the topic on July 23, when he pointedly advised Japanese Prime Minister Shinzo Abe — who plans to deliver a speech marking the anniversary — to convey genuine contrition for the suffering caused by Japan’s aggression. “We will be watching how Japan sums up its past and shows sincerity to the victimized countries,” said the ambassador. Abe and other Japanese leaders have acknowledged their country’s crimes during the war, but their apologies have tended to be grudging or awkward. Frequently they have been undermined by truculent rationalizations, or by suggestions that Japan’s ugliest wartime offenses might still be open to debate.

The cruelties Japan inflicted on China, Korea, and other Asian nations in the 1930s and 1940s — mass murder, slave labor, biological and chemical warfare, human experimentation, and the forced sexual enslavement of hundreds of thousands of girls and women — truly were horrific. Beijing’s demand for a more convincing display of penitence from Japan for what it did to so many helpless Chinese victims is not hard to understand.

But when will we hear a heartfelt apology or see meaningful atonement for the equally ghastly horrors inflicted on countless Chinese victims by their own government?

No force in history has shed more innocent Chinese blood than the Communist regime that has ruled since 1949, when Mao Zedong seized power and officially proclaimed the People’s Republic of China. The Japanese occupation had been ruthless, as had the massive civil war between Chiang Kai-shek’s Nationalists and the forces commanded by Mao. But with the reign of the Communist Party came violence and terror on a scale China had never before known.

In the first decades of Mao’s rule, wrote Jean-Louis Margolin in the acclaimed Black Book of Communism, a 1999 survey of the world’s Communist regimes, “there were between 6 million and 10 million deaths” that were directly caused by government action. But that’s only where the tally begins. To those victims add the “tens of millions of ‘counterrevolutionaries’” swept into Mao’s prisons and labor camps, “with perhaps 20 million dying there.” Add as well the appalling death toll during the Great Leap Forward, Mao’s calamitous campaign of forced collectivization and abolition of private agriculture, which caused a famine of more than biblical proportions, starving more than 40 million Chinese in less than three years.

There is also the genocide in Tibet, where between 10 and 20 percent of the population was wiped out by the Communist invasion. Millions more were massacred in successive ideological purges and terror campaigns and the totalitarian derangement of the Cultural Revolution. All told, China’s ruling Communist Party has annihilated an estimated 65 million Chinese men, women, children, and babies. Japan’s enormities, unspeakable as they were, don’t come close.

The recitation of dry casualty statistics cannot begin to convey what China’s victims suffered.

“Tibetans not only were shot,” the Dalai Lama said of the carnage unleashed on his homeland during the 1950s, “but also were beaten to death, crucified, burned alive, drowned, mutilated, starved, strangled, hanged, boiled alive, buried alive, drawn and quartered, and beheaded.” The Chinese government complains that Japan’s remorse for its imperial crimes don’t go far enough or seem sincere enough. The Chinese government’s remorse for its own crimes of occupation and repression, meanwhile, is nonexistent.

Mao, who outdid even Hitler and Stalin in mass murder, once contrasted the performance of the Communist Party with that of an emperor infamous in Chinese history for his savagery: “What’s so unusual about Emperor Shih Huang of the Chin Dynasty? He had buried alive 460 scholars only, but we have buried alive 46,000 scholars!”

Burial alive is only one of the countless terrors China’s rulers have visited upon China’s people.

“Mutilation was carried out everywhere,” writes historian Frank Dikötter in Mao’s Great Famine, his gripping 2010 chronicle of life during the Great Leap Forward. “Hair was ripped out. Ears and noses were lopped off.” He recounts how a man named Wang Ziyou was penalized by party bosses in Hunan Province: “One of his ears chopped off, his legs were tied up with wire, a 10-kilo stone was dropped on his back, and he was branded with a hot iron — as punishment for digging up a potato.”

Yet to this day, Mao is revered by China’s government; a 15-by-20 foot portrait of the “Great Helmsman” dominates one end of Tiananmen Square. There is not even a modest plaque to recall the hundreds of prodemocracy protesters gunned down by Chinese troops in 1989 — a massacre the government still refuses to acknowledge, much less apologize for. Just as it refuses to acknowledge or apologize for all the other crimes it has committed against the people of China.

Long after Japan’s cruelties in China ended, those of Mao and the Chinese Communist Party were just getting started. When will Beijing stop dwelling on the remorse due from Japan, and start doing penance for its own monstrous sins?

Jeff Jacoby is a columnist for The Boston Globe.