They are known as "idols" and their job is "to sell dreams". For decades, the young pop stars of Japan and South Korea have been the envy of teenagers. But behind the glamour, the lucrative industry is run by talent agencies with an iron fist. Two recent apologies by Japan's popular band SMAP and Taiwanese star Chou Tzuyu have highlighted just how much power they have. Both J-pop and K-pop - as Ja