One day monsters appear in Kakyou City. The school Chiyoko and Haruka are in shakes like during an earthquake and the window panes shatter all at once. During the commotion, the two rush to the rooftop. What they see are bodies lying in the street and smoke in the distance.
There, a strange talking cat approaches them and asks them to become 'warriors' in order to fight against these 'Biomonsters'. Panicked, Chiyoko is first to agree. She receives a round gemstone-looking transformation device along with a rather painful needle to the spine. Now a 'warrior', she is able to travel faster than the speed of sound and put up a fight against the monsters. But it is no cakewalk. The first battles are panicked and teeth-gritting. Even with Haruka joining her, they barely are able to fend off the first wave. The cat tells Chiyoko and Haruka they have to search for more students with the potential to become 'warriors' like them. Over the next few weeks they continue searching for members, however, Chiyoko's reputation as a dangerous person and her slight lack of common sense don't do them any favours, as she ends up frequently misunderstood. But besides that, not everyone isn't so willing to risk their life. Why should they be? This isn't the army. No-one is there to force them to join, or to maintain order.
How does it feel like to be part of a group with other students risking your life to protect your city? What are you going to think of the other people there? You share a secret in common with these people, you're risking your life beside these people. But are you really all just going to become comrades?
Some reach out and interact with others. Some reach out to their friends anew. Others sit back and watch anxiously, or perhaps in disapproval. Even while the threat of annihilation grows, their personal worries all remain in the air.
The days ahead lay filled with turmoil, large and small.