Kajiura started the Kalafina music group in 2007 to perform the theme songs for The Garden of Sinners anime films.
The official website had revealed that the other two singers Wakana and Hikaru Masai would continue to work on musical activities.
Yuki Kajiura, the founder of Kalafina, left the Space Craft Produce agency in February.
The group started out with four members, with two of the four members — Keiko Kubota and Wakana — having previously worked with Kajiura under her FictionJunction project.