It's a case of the tail wagging the dog, or, in this case, the duck. AFLAC Inc. ( AFL ), a Columbus (Ga.) supplemental health insurer, raised its brand recognition enormously in the U.S. with TV commercials featuring a duck that incessantly quacks "Aaaa-flaaaak." AFLAC isn't using the duck right now in its Japanese ads, but no matter: The company's business in Japan dwarfs its home market, accounting for 70% of AFLAC's operating earnings and 80% of its $38 billion in assets. Indeed, American Family Life Assurance Co., or AFLAC, is the largest foreign insurer in Japan and second-most-profitable gaijin company, after IBM. Merrill Lynch expects pretax Japanese profits to reach $940 million this year, up 14% from last year. Japanese revenues are expected to rise 5%, to $7.6 billion. "Japan is our driving force," says AFLAC Chief Executive Daniel P. Amos.