The world is at peace, but there are still everyday dangers. So, a new breed of protectors, known simply as "Heroes" have arrived on Earth. Shy is Japan's new Hero, but is she ready to be a Hero? What does it MEAN to be a Hero anyway?

Shy returns to school only to find herself faced with Iko Koishikawa, a girl whose injuries she blames herself for. As if that wasn't stressful enough, a mysterious young boy sows discord and forces the girls to face the darkness in their hearts.