ハロー!プロジェクト・キッズ
were a short-lived Japanese pop group made up of five Hello! Project Kids members led by Mari Yaguchi of Morning Musume. Yaguchi acted as a mentor and the group released two singles. ZYX is important in that it is the first unit that Hello! Project Kids officially joined with the second being Aa! formed in 2003, the third being Berryz Kobo in 2004, and the fourth being Cute in 2005. As Saki Shimizu and Momoko Tsugunaga were selected to become members of Berryz Kobo in 2004, the activity of ZYX ended.