There are monsters called ‘Umbiz’ that kill humans and eat them, along with ‘Umbiz’ are these things called ‘Shadows’. ‘Shadows’ are inhumans who posses abilities and strength, they’ve been captured and a few of the most powerful were tested. ‘Shadows’ are entrusted to kill the man eating ‘Umbiz’ working for a company named Akari. They are also assigned handlers who take care and keep them in line