A strange and curious transformation happens inside some of the Holy City’s best Asian restaurants late at night after the last plate hits the sink. The sushi cart rolls out, and the deejay cart rolls in. Smiling chefs in white hats step from behind the glass partitions, and a burly bouncer posts up at the door. The candles on the tables go out, sometimes the tables themselves are taken away, and diners make way for dancers.

Many sushi bars — here in Charleston and around the world —undergo this metamorphosis every weekend. In fact, the late-night dance scenes at Wasabi on State Street and Tsunami on East Bay Street are so popular that the two restaurants are often among Charleston’s top 10 clubs in online rankings. The question, of course, is why?

Steve Palmer, managing partner for the Indigo Road Restaurant Group, initially tried to resist the pull of the late-night crowd after opening O-Ku on King Street in 2009. Indigo Road’s portfolio, after all, includes such food-snob dens as Oak Steakhouse and The Macintosh. But Palmer’s 29-year-old general manager Kimball Brienza reminded him that he’s pushing 43 and that maybe he should let Brienza handle the entertainment side at O-Ku. So Palmer did a little market research and found that serious restaurants in New York, Las Vegas, and even Tokyo uphold the idea of sushi bars becoming nightclubs. And so Palmer brought in a deejay on Saturday nights after 11 p.m. with one caveat. “We have to be a restaurant first,” he says.

One year later, O-Ku’s bar sales have grown, while dinner business remains as lively as ever. Of course, not every restaurant under the Indigo umbrella is primed for a post-dinner makeover. “We would never do that at The Macintosh,” Palmer says. “There’s something about Asian restaurants that lends itself to this.”

So what is it?

For starters, sushi is not just tasty, it’s fun to eat. How often have you ordered a roll — let’s say something with a truly wacky combination of ingredients crafted into beautifully constructed little works of edible art — while out dining with friends and eaten the entire thing yourself? Never. And that’s because sushi is meant to be shared.

Of course, there are other reasons restaurateurs opt for a late-night transformation. According to Anthony Tanzini, manager at Tasty Thai on King Street, it’s simply good for business. Sometimes, he says, pushing back the closing time can add $3,000 to the till by the end of the night. “People who come to party on a Saturday night, they’re in here Sunday afternoon eating,” Tanzini says.

Although sushi bars often effortlessly evoke the spirit of indulgence and sensuality, that’s not to say some restaurants don’t try harder than others. Take Cheetah’s in New York, for example. They serve sushi atop the naked bodies of its “Cheetah girls” in a nod to the ancient Japanese practice of nyotaimori, or “body sushi.” Charleston’s sushi bar/nightclub phenomenon is far more tame.

Jonathan Smyers, who manages Wasabi’s Daniel Island restaurant, says his business sticks to live entertainment outside on the patio, not club music. Meanwhile Bushido in West Ashley, featured on the Travel Channel’s Man vs. Food for its Spicy Tuna Roll Challenge, brings in bands on Fridays, and serves half-price select sushi at midnight, according to manager Gabriel Balagtas.

And since July, Tsunami downtown has limited its deejay nights to Thursdays. However, general manager John Choi says diners still come in late on Fridays and Saturdays and that the kitchen stays open to serve them. “We don’t want to be the nightclub scene,” Choi says. “We’re committed to being a restaurant.”

But at the downtown Charleston Wasabi, the dining room tables in the private party room disappear on Fridays and Saturdays around 10:30 p.m. and the Top-40 dance music cranks up. “It’s always good sushi,” says general manager Dwi Cahyono. “But you stay at the restaurant for good music and good people.”