DEF.DIVA is a "special group" formed in 2005 from the Hello! Project idol umbrella and consists of Aya Matsuura, Maki Goto, Natsumi Abe, and Rika Ishikawa. The band's name is an abbreviation of the phrase "Definite Diva".
Three of the members of DEF.DIVA (Goto, Abe, Ishikawa) were previous Morning Musume members, while Matsuura is a soloist. Goto and Abe are now also soloists and Ishikawa leads v-u-den. Goto, Matsuura and Abe also composed a previous three-member special group, Nochiura Natsumi. The four were joined together in September 2005 to form DEF. DIVA.
Currently, the individual members are involved in other projects, with Abe's and Goto's solo careers and Ishikawa's status as leader of v-u-den taking priority over DEF.DIVA. Matsuura, meanwhile, is involved in a new duo, GAM with fellow Gomattou member Miki Fujimoto as well as continuing her own solo career.