Having too much of a good time lately? Well, have a seat in T.F. Mou’s history class as he screens Black Sun: The Nanking Massacre for you. Chances are, you’ll lose that smile on your face for the rest of the day. Or the week. Heck, if you’re sensitive enough, it might never come back.

Gorehounds and other black-hearted souls know Chinese filmmaker Mou as the director of the stomach-churning Men Behind the Sun, his no-holds-barred depiction of the Japanese Army’s monstrous medical experiments conducted upon the Chinese during World War II. Black Sun is that film’s official sequel (Men Behind the Sun 2: Laboratory of the Devil and MBTS 3: Narrow Escape are in-name-only cash-ins from Hong Kong hack Godfrey Ho), and like its predecessor, it’s based on true war crimes committed by the Japanese, and pulls no punches in depicting the horror that was carried out in the name of combat.

In a nutshell, the Nanking Massacre occurred during the Japanese invasion of China in 1937. The subjugation of that country had long been a goal of Japan, which viewed their neighbors as a stepping stone to total world domination. Realizing that China was far too large to conquer by means of conventional warfare, the Japanese tore up the rulebook and unleashed a torrent of rape, murder, and mass execution on the Chinese population. The assault on Nanking (also known as “the Rape of Nanking”) took place in December of 1937 and lasted until March of 1938; during that time, an estimated 300,000 soldiers, civilians and prisoners of war were killed (for a little perspective, that’s like wiping out half the population of Boston, MA). The lucky ones died in mass firing squad executions; other less fortunate individuals were burnt or buried alive, used as live target practice, crushed under tank treads, or simply served as a neck to test the sharpness of the Japanese officers’ swords. Of that mind-boggling number of casualties, 80,000 were women and young girls who were forced into prostitution or raped outright; if you’re curious and sick enough, you’ll also find plenty of photos of piles of butchered infants taken during this human harvest. The Japanese army had been raised to regard the Chinese as less than human (in Men Behind the Sun, the Chinese prisoners are referred to as “maruta,” which translates loosely into “wooden log”), and had no trouble encouraging their soldiers to conduct competitions for the highest body count.

And that’s essentially what you see in Black Sun. There isn’t much of a linear story to the film, nor is there a central hero or villain on which to pin your hopes or hatred; it’s more concerned with depicting the atmosphere of all-encompassing, inescapable despair and terror that settled on Nanking like a black and noxious cloud during that period. Blood junkies hoping for a downpour of gore like Men Behind the Sun might be disappointed, since the violence is relegated to a handful of decapitations and frequent beatings and shootings, though the film’s “standout” effect is show-stoppingly hideous (let’s just say that you’ll want to put down your popcorn while it’s happening). But really, the movie could be up to its knees in fake blood, and it still wouldn’t have the gut-punch impact of scenes like a courtyard littered with human heads, or a procession of monks going quietly to their deaths, or most stunning of all, a mass cremation of 5000 bodies on a beach. And Mou deepens the impact of these scenes by frequently cutting to actual photos, footage and eyewitness testimony taken from the massacre that illustrate the terrible reality and truth behind what might be easily dismissed as imagination. In terms of its ability to make painfully clear the mind-numbing horror of human behavior during wartime, Black Sun has almost no equal – only Pier Paolo Pasolini’s Salo comes closest to leaving a similar mark on the viewer’s mind and soul.

Unearthed Films clearly (and appropriately) views Black Sun as an important film and not exploitation, and gives the film a DVD presentation (its first in the U.S.) with an appropriate degree of respect, with a host of fascinating extras that provide supplemental information on the Nanking Massacre. Mou himself is interviewed twice (in text-only format, unfortunately), and discusses the challenges he faced in making Black Sun and Men Behind the Sun, most notably from the Chinese government and younger Japanese viewers, who were largely unaware of these events. Most Americans have been kept in the dark of the Japanese atrocities in China as well, so lengthy overviews of the conflict have been included in the supplemental features, most notably an hour-plus U.S. Army propaganda film from WWII that features footage taken during the occupation of Nanking and smuggled out by an American missionary. For those needing a break from the gloom, there are also trailers for “lighter” Unearthed DVD titles, including Junk and Evil Dead Trap 2. Compared to the main feature, they play like the Teletubbies.