The Ryu-Jitsu at NAO Salon and Spa in New York is an extraordinary treatment that blends exercise, detoxification, and massage. In two surreal hours the Ryu-Jitsu (which means "dragon magic" in Japanese) burns fat, softens your skin, and uplifts you to a state of overall well-being. It begins with a series of standing, squatting, and sitting positions on a Body Master passive treadmill, which shakes and vibrates so fast that all your core muscles contract. Next, you are brought to a bed of heated lava stones from deep below Mount Fuji, which are used for their healing and detoxifying properties. After you spend 20 minutes lying on the stones and sweating out toxins, the therapist begins a combination Thai-shiatsu massage on a special dry-float water bed that is firm during the treatment and sinks down into the water post-massage, warming and enveloping you. You then lie wrapped in a sheet, floating into deep relaxation in this cushiony womblike cocoon. Treatment, $350. At 609 Madison Ave.; 212-752- 1111. Water bed, $22,795; spavisions.com.