Soft-drink giant PepsiCo will break a long-standing Japanese taboo on comparative advertising when it unveils a television commercial here this week showing arch-rival Coca-Cola's top product.

The advertisement, to appear March 16, features rap artist M.C. Hammer who goes offstage during a performance to quench his thirst with a Pepsi but is shown downing a clearly labeled Coca-Cola by mistake.When he returns to the stage, he shocks his audience by starting to croon the often-parodied and syrupy love song "Feelings." After quaffing a Pepsi handed to him by a young fan, he immediately reverts to his usual fast-paced style.

Japanese companies have traditionally been shy of airing commercials that openly challenge competitors. Japan's Fair Trade Commission bars advertisements that do not compare products objectively or that slander another company's product.

PepsiCo won commission approval for the commercial because it does not say Pepsi is better than Coca-Cola in any way, a spokesman for Pepsi Cola Japan said.