Are you now or have you ever been a 14-year-old Asian girl? If not, chances are you're unfamiliar with Rain, the Korean teen-pop phenomenon born Jung Ji-Hoon. But in the Far East, the 27-year-old performer is Joe Jonas, Usher, and Pikachu all in one: a button-cute, merchandise-spewing, faintly lascivious tween magnet. He's sold millions of CDs, filled 40,000-seat arenas, acted in soap operas, and caught the attention of pop-music cognoscenti like Diddy. Now he's making a bid for fame in the United States, starring in Ninja Assassin, a special-effects-laden martial-arts film from the Wachowski brothers (of The Matrix fame). It's a smart strategy: Korean pop has yet to find a global audience, but everybody speaks kung fu.