Although most personal information about her is unknown, in 2012, she revealed via letter her real name to a famous radio station in Tokyo, and that her real given name is also Annabel.
She began her musical career in 2005. In 2006, she and singer Nagi Yanagi formed the unit Binaria; to date, they have released 13 albums. In 2007, she formed another unit with singer Bermei.inazawa called anNina. As anNina, the duo performed the ending themes to the second and third seasons of Higurashi When They Cry. In 2009, she started her career as a solo singer.
Due to her rise in popularity, she started performing theme songs for anime series. Her first solo single was "Anamnesis," which is used as the ending theme to the 2012 anime TV series Another; the single for "Anamnesis" was released on February 8, 2012. Annabel released her second single "Above Your Hand" on May 23, 2012, which is used as the ending theme for the anime TV series Sankarea. Her third single, "Signal Graph," was released on July 25, 2012, which is used as the opening theme for the anime TV series Love, Elections & Chocolate. She released her first solo album Miniascape on November 28, 2012.