Pretty Rhythm
was a pre-debut trainee group who accompanied Prizmmy as a supporting act. They appeared with Prizmmy in hosting the "Pretty Rhythm Studio" segments in ' and "Pretty Rhythm: Rainbow Live". The members also appeared in their music videos as their back-up dancers. Prism Mates also made a cameo in episode 9 of '. At the time, the members' ages averaged around 11.2 years old.