While at the time relatively short-lived, Onyanko Club, formed in Tokyo in 1985, have left a legacy that has made them perhaps the most significant female idol group of the '80s. The initial lineup of 11 members was put together under the aegis of producer Yasushi Akimoto, from participants chosen through the Fuji TV audition show All Night Joshikosei Special, but subsequent, frequent lineup changes resulted in more than 50 girls passing through the group's revolving door membership policy.
Onyanko Club debuted in April of 1985 via their own TV show, Yuyake Nyan Nyan, but the group were soon rocked by scandal when later that same month, six members were caught smoking by a photographer for a weekly gossip magazine; they were promptly fired. The new lineup, including Akimoto's future wife, Mamiko Takai, went on to achieve immediate chart success with their debut single, "Sailor Fuku wo Nugasanaide," which, in contrast to the group's puritanical internal regime and plain, girl-next-door image, featured unusually sexually direct lyrics that played with the idea of Japanese schoolgirl uniform fetishism, and reached number five in the charts. The follow-up, "Oyoshi ni Natte Teacher," followed along the same lines, reaching number two with a lyric detailing a schoolgirl's flirtations with her teacher in the hope of improving her math grades while resisting his attempts to go further. The following year saw the single "Otto Chikan!" (dealing with sexual molestation on a crowded train), which set off a string of five number one hits, as well as the film Onyanko the Movie: Kiken Ippatsu.
In addition to their vast number of ever-changing members and sexually questionable lyrics, Onyanko Club were also notable as pioneers of the spin-off band concept, with the groups Ushiroyubi Sasaregumi, Nyangilas, and Ushirogame Hikaretai all featuring members of the wider Onyanko Club family. The group disbanded in 1987, but their precedent (minus the overtly saucy lyrical content) would go on to form the basis of the successful '90s/2000s idol franchise Morning Musume, and Akimoto's own later creations AKB48 and SKE48, all of which trace their lineage back to Onyanko Club's marketing and production format. The legacy of the group also had a more immediate impact, with several "graduating" members going on to have solo careers, most notably Shizuka Kudo, who had a string of Top Ten hits (including 11 that reached number one) between 1987 and 1994.