A group of friends have customized their microwave so that it can send text messages to the past. As they perform different experiments, an organization named SERN who has been doing their own research on time travel tracks them down and now the characters have to find a way to avoid being captured by them.

The Sakuragoaka Girls' Academy curriculum traditionally focuses on the three "R"s of reading, writing and arithmetic, but Ritsu Tainaka wants to add two more "R"s: Rock and Roll! To do that, however, Ritsu has to save the Light Music Club from being shut down due to little problems like not having any other members or a faculty advisor. After strong-arming her best friend Mio into joining and convincing Tsumugi Kotobuki to make it a trio, Ritsu's would-be rockers are soon only one talented guitarist short of the quartet they need for school approval. What they get, unfortunately, is Yui Hirasawa, who's never held a guitar in her life, but she's determined to learn! Will the school halls come alive with the sound of music?