Yuna Yuki, her best friend Mimori Togo, and sisters Fu and Itsuki Inubozaki, are all members of the Sanshu Middle School Hero Club, which is dedicated to helping those that request it via their website. During class one day, upon each receiving a strange ‘forestize warning’ message on their phones, the four girls find time has suddenly stopped around them before they are enveloped by a rainbow-colored light, soon finding themselves in a strange colorful forest.