Their hips swathed in tight, colorful skirts, and their shoulders bare above tight tube tops, about 30 women shimmy and shake sexily to fast, powerful drum rhythms and the cheerful melody of Tahitian banjo.

"Move your hips around in time with the music! One, two, three, four . . . " urges Ayumu Mahealani, whose ringing voice as the Tahitian dance instructor at classes in Sandii's Hula Studio in Harajuku, Tokyo, both instructs and encourages at the same time.

While hula dance, taught in numerous hula schools and sports gyms, has been popular around Japan for several years, Tahitian dance is now following in its (bare) footsteps for the same reasons — that it's fun and good for losing weight, especially around the waist.