Staying at the top of the game after 10 years is no mean feat in Japan’s fickle music business. As one of the first artists to bring American-style R&B to these shores, Double’s achievements are doubly impressive. And now she’s celebrating her first decade with an album of collaborations with Japanese and American artists such as De La Soul, Ak’sent, AI and Kreva. To top it off comes “Black Diamond,” a pulsating duet with self-styled “Queen of hip-pop” Namie Amuro.