The scene is Tokyo in 2031 AD. The world has become too polluted for the majority of the people to live without special shields to protect the air they breathe. Kou, Rika, and Dariru, however, still live in the streets, because they are genetically stronger than the majority and can withstand the stronger UV rays and the dirty air. They are part of the rebel underground community. One day, Kou discovers another secret. A ring that he received from his scientist father seems to have special powers... Who is this girl that he is now in contact with and why does she know so much about him?