The “it girl” in Williams’s music video is a very young-looking cartoon character.

What are we to make of Pharrell Williams’s latest video for “It Girl,” which features the hip-hop star singing, “Hold my hand, and moan again, I’ma hold that ass” to images of what appears to be a prepubescent cartoon girl? Although seemingly well received (it has been viewed more than two and a half million times on YouTube since its release on September 30th), the video has left some American critics struggling to describe the experience of watching it. Pitchfork lauded the work as “an animated epic,” while a more cautious Rolling Stone dubbed it, incongruously, “Pokémon-inspired.” It seems to have bewildered fans, too. Debates have sprung up on various blogs: “Why did he choose such young characters?” wondered one viewer on Tumblr, who declared the video “creepy.”

The confusion shouldn’t be surprising. While Pharrell’s breezy tune is steeped in the idioms of American hip-hop and dance culture, the video for “It Girl” comes from the world of Japanese otaku—obsessive fans of anime, manga, and video games. The co-directors and creative architects of the video are a pseudonymous pair of Japanese artists: the textile designer Fantasista Utamaro and the secretive painter known only as Mr. The latter is a protégé of the pop artist Takashi Murakami and a core collaborator in Murakami’s Kaikai Kiki art collective, under whose banner the video was produced. Born in 1969, Mr. rose to prominence as a contributor to Murakami’s 2001 travelling exhibition “Superflat” and its successful 2005 follow up, “Little Boy.” He also happens to be, by his own admission, a lolicon.

A Japanese term derived from the English phrase “Lolita complex,” lolicon describes a fascination with cartoons of very young-looking girls engaged in varying degrees of erotic behavior. (The word can be used to describe both the genre and its aficionados.) What can really confuse non-Japanese is that lolicons, who exist in large numbers in Japan, actually prefer illustrated art over real or photographic portrayals of girls, a predilection that’s known as a “2D complex.” This one-step removal from reality is the genre’s key feature, and it’s what keeps lolicon legal—if still, as non-fans note, “creepy.” Almost all of Mr.’s work is related to lolicon; in a 2007 interview, he described his efforts as a sort of safety valve, “releasing my fantasy world through my work instead of acting it out in real life.”

Lolicon is the dark matter of Japanese pop culture, infusing everything from best-selling comics and animation to the nation’s ever popular girl groups. Yet it’s almost never discussed in polite society. Indeed, the very term is something of a four-letter word in Japanese, virtually synonymous with pedophilia. When I recently spoke about lolicon to a comic-book-artist friend—an industry veteran who dabbles in erotica herself—she lowered her voice to a whisper whenever she uttered the term.

Lolicon emerged in Japan in the late nineteen-seventies as self-published fan parodies of popular female manga characters. Something like the Tijuana bibles of the manga world, they exposed the eroticism hinted at in the curvaceous young cartoon beauties of the mainstream. Lolicon’s arrival, perhaps not coincidentally, accompanied the coming of age of the first generation of boys who had been raised on manga and anime, and the runaway popularity of these amateur pornographic productions triggered a flood of similar content in Japan’s vibrant professional comic industry. For a time, lolicon seemed poised to go mainstream. But in the end it remained a skeleton in the closet, reaching only domestic audiences as more palatable sci-fi and fantasy fare, such as the apocalyptic cyberpunk epic “Akira” and the early films of the director Hayao Miyazaki, built the foundations of “Cool Japan” abroad in the nineteen-eighties.

The shadow culture of lolicon triggered a great deal of soul searching in 1989, when a young man by the name of Tsutomu Miyazaki was arrested and convicted for the serial killings of four elementary-school girls in a Tokyo suburb. The Japanese press, desperate for a way to explain the inexplicable horror of these crimes, seized on the presence of anime and manga in Miyazaki’s cluttered bedroom to label him an “otaku murderer.” Given the immense popularity of all sorts of illustrated entertainment among young Japanese, many critics felt the connection was a stretch. Despite lolicon’s inherent ickiness to outsiders, it has never been definitively linked to Miyazaki’s case or to other instances of criminal behavior.

Still, the headlines sent lolicon underground for many years, and in the nineteen-nineties creators reared on the genre absorbed, defanged, and desexualized it for the mainstream. Today, it has morphed into an animation style called moé, after a kanji character meaning both “burning” and “bursting into bud.” In moé, sexuality is treated indirectly; rather than showing overtly pornographic images, it focusses on “slice of life” dramas that allow consumers—mainly adult men—to observe the budding sexuality of pre-teen and teen-age girls from a discreet remove.

This brings us back to the video for “It Girl,” which makes sense only when viewed through the lens of lolicon and moé. Pharrell isn’t the first American musician who has collaborated with Kaikai Kiki: in 2007, Murakami provided the cover art and directed the title video for Kanye West’s album “Graduation.” But, whereas Murakami had the safety of Kanye’s cuddly Dropout Bear mascot to riff on, Mr.’s vision for “It Girl” strays into far more personal territory. It’s hard not to feel unsettled by the sight of Pharrell’s cartoon avatar peeping through binoculars at a group of Lolitas frolicking in the surf. Whether the fact that the girls are animated makes it less disturbing is a matter of personal taste. But bilingual viewers can find clues to Mr.’s intentions throughout the video.

The protagonist of “It Girl” is a girl named “Yoshic[ch]!!,” a nonsensical affirmation that is prominently displayed several times in Japanese in the course of the video. The very same phrase is also splashed in Japanese across the canvas of Mr.’s 2011 painting “Okay!!,” which features a girl dressed in a traditional schoolgirl outfit jubilantly lifting a leg to flash the viewer. (The work sold for the surprising sum of a hundred and fifty-two thousand dollars in a Christie’s charity auction benefitting victims of the 2011 earthquake and tsunami in Japan.)

Many of the video’s references are well known to Americans. The pixilated graphic interludes are instantly recognizable to anyone who’s ever played a video game, for instance. But other tropes are less familiar, such as eighties yankii juvenile-delinquent culture, or nineties “dating simulator” games, a favorite of love-starved otaku, which are parodied in a scene in which Pharrell gifts Yoshic[ch]!! a yukata robe. Several of Yoshic[ch]!!'s friends—a girl in eyeglasses; a cute girl wearing a hostile facial expression—represent archetypal moé characters.

For foreign viewers, the most difficult aspect of the video might be the idea that the “it girl” for one of America’s most popular singers could be a cartoon child. It’s impossible to know how well Pharrell and his people understood Mr.’s work when they commissioned Kaikai Kiki to produce the video, or even after they saw the finished product. Re-packaging edgy Japanese pop culture for unwitting foreign audiences is one of Kaikai Kiki’s signature moves.

In 2005, the art collective’s travelling installation “Little Boy,” named after the atomic bomb dropped on Hiroshima, made its subtext clear with the subtitle “The Arts of Japan’s Exploding Subculture.” The “It Girl” video suggests that Mr. and his cohorts aren’t finished dropping their bombs on an unsuspecting America. Even if one knows enough about the video’s influences to feel more than a little uneasy with its implications, you have to hand it to the directors for transforming two million Americans into unwitting lolicon consumers, even if for only the duration of a pop song.