Insomnia is spread all over the world and a new species, known as the "Bloodthirsty," has been born as a side effect from the medicine made to cure the disease. The main character, Ryuu Mi, who is a child of a bloodthirsty and human, is considered to be the child to unite the species. However, Ryuu Mi gets arrested due to a bank robbery and becomes the main suspect in the case. He tries to escape the jail with help of his father, who is a bloodthirsty but work as a human in the Ministry of State Security Special Management Office, which investigates the bloodthirsty. Suddenly an unknown monster attacks the jail, and even though Ryuu Mi is able to escape the monster with his inmate Anji, he discovers that the jail is located in Aori, a deserted city and the birthplace of the bloodthirsty species. Why are captured bloodthirsty being sent to Aori? What was the monster? Being forced to get involved in the battle against the monster, Ryuu Mi begins his journey to solve this mystery.