The story is set at the beginning of the 21st century with a population devastated by bio terror. Now there are two types of people. One is Nokusu who are infected but survived and consequently they carry antibodies. Most are young, healthy and have high intelligence, but they have a high sensitivity to ultraviolet light and active, especially at night. Another group is Kyurio. They survive by never had the virus. The Nokusu discriminate Kyurio. Tetsuhiko Okudera is Kyurio. He was born in a poor village. He was not happy with being Kyurio and hope he can be Nokusu. Yui Ikuta is a childhood friend Tetsuhiko this. He tried to revive the rural poor.