Berryz Koubou are a Japanese band based on the Hello! Project Kids, a project of the idol agency Up-Front. BK's size can be said to be bigger than the scope of their success: the group features seven members, all vocalists (there were eight until 2008), but none of their first five albums managed to sell over 20,000 copies, and none of the 20 singles of the same period shifted over 40,000 CDs, although the sheer number of releases still makes for some nice sales figures.
The name of the group translates as "Berryz Workshop," and the band was initially meant to include a revolving cast that would eventually feature every member of Hello! Project Kids. The gimmick was dropped fast, and the band settled on a permanent lineup including Saki Shimizu, Momoko Tsugunaga, Chinami Tokunaga, Maasa Sudo, Miyabi Natsuyaki, Yurina Kumai, Risako Sugaya, and Maiha Ishimura, with seven other Hello! Project Kids going on to form C-ute. All members of Berryz Koubou, despite being very young, already had previous showbiz experience: they worked as backup dancers in W's promo videos, participated in Aa! and ZYX, and appeared in the movie Okashi na Daibouken starring the band Mini Moni. The newly established group kicked things off with their own radio show, which ran in 2004-2009, and debuted in 2004 with a trio of singles ("Anata Nashi de wa Ikite Yukenai," "Fighting Pose wa Date ja Nai!," "Piriri to Yukou") followed by their first studio album 1st Cho Berryz. In 2005, Ishimura "graduated" from the project to concentrate on her education, but the rest of the girls pressed on, releasing the second album, Dai 2 Seichouki, and the EP, Special! Best Mini 2.5 Maime no Kare, within a month of each other (both were out in 2005). They continued to release one record a year, popping out the EP 3 Natsu Natsu Mini Berryz in 2006, and the full-lengths 4th Ai no Nanchara Shisu in 2007 and 5 (Five) in 2008. In 2007, they also broke the record for the group with the youngest members to play an arena: they sold out the 20,000-seat Saitama Super Arena with the bandmembers averaging less than 14 years old, thereby beating Morning Musume, who held the previous record with 16.3 years. 2009 was marked by Berryz Koubou first best-of collection, which sold 13,000 copies -- the same amount as their studio albums.