Omg, major bump to this thread, because there is new info!
http://headlines.yahoo.co.jp/hl?a=20...000046-spn-ent
She's going to release her first single in Japan on 3/3, years since being active as a talent and singer (as part of Black Biscuits).
Official site at Universal:
http://www.universal-music.co.jp/vivian/ (song starts playing immediately)
Her press conference:
Her best selling single as Black Biscuits: