Too bad it's right in he middle of her concerts! I don't really have anything to add since Deli and true pretty much gave all he good advices. But Koda Kumi will do her return concerts in November and Namie Amuro will have her Dome tour during December. The Tokyo Dome dates is quite late but maybe other cities is earlier. Sorry I dot remember clearly but it's easy to look up!
One last thing I can offer is that I live in Tokyo and do you ever feel the need to go karaoke and sing Ayu songs I'm always up for that!