ZYX was formed in 2003 and featured Morning Musume's Yaguchi Mari and five members of Hello! Project Kids. The group released only released two singles. No more releases from the group gave it the status of being a special unit in Hello! Project.
In the summer of 2009, Hello! Project released a cover album that featured seven special units that included all the members. ZYX was featured as ZYX-α with a new line-up.
It should be noted that ZYX is pronounced as one word, "zicks" ("jikkusu" in katakana), rather than being spelled out letter by letter (not "zee-why-ecks").
First Generation (2003)
Yaguchi Mari (矢口真里, leader) (Morning Musume)
Umeda Erika (梅田えりか) (Hello! Project Kids)
Shimizu Saki (清水佐紀) (Hello! Project Kids)
Yajima Maimi (矢島舞美) (Hello! Project Kids)
Tsugunaga Momoko (嗣永桃子) (Hello! Project Kids)
Murakami Megumi (村上愛) (Hello! Project Kids)
Second Generation / ZYX-α (2009–)
Niigaki Risa (新垣里沙, leader) (Morning Musume)
Kusumi Koharu (久住小春, graduated December 2009) (Morning Musume)
Tsugunaga Momoko (嗣永桃子) (Berryz Kobo)
Tokunaga Chinami (徳永千奈美) (Berryz Kobo)
Sudo Maasa (須藤茉麻) (Berryz Kobo)
Umeda Erika (梅田えりか, graduated October 2009) (°C-ute)
Wada Ayaka (和田彩花) (S/mileage)
Ogawa Saki (小川紗季, left September 2011) (S/mileage)