Haruka Tomatsu
Balloom was created in March 2011 by , who asked seven other musicians who were popular on Niconico Douga in 2009 to join the label. Four founding members of the label, Wowaka, Toku, Fullkawa Honpo and Hachi (Kenshi Yonezu) formed a production collective called "Estlabo" to work on the ending theme song of the anime "", a cover of Zone's "Secret Base (Kimi ga Kureta Mono)" sung by voice actresses Ai Kayano, Haruka Tomatsu and Saori Hayami.