Taiyô plot
At the beginning of the 21st century, the earth's population was considerably decimated by bioterror. There are now two types of people: Nokusu, who are infected by a virus, but who are resistant to it. Most are young, intelligent and healthy, but they are very sensitive to ultraviolet radiation, so they can only be active at night. The other species is the Kyurio, who have never had the virus. They are discriminated against by the Nokusu. Tetsuhiko Okudera is a Kyurio and was born in a poor village. He would like to be a Nokusu.