"Rainbow Sonics" is a fictional band featured in the popular Japanese anime series "K-On!". The band consists of four members, Yui Hirasawa, Mio Akiyama, Ritsu Tainaka, and Tsumugi Kotobuki. Rainbow Sonics is known for their catchy music and energetic performances, and they are a central part of the storyline in "K-On!". The band's name reflects their colorful personalities and their ability to bring joy and excitement to their fans.