High school student Keita Ibuki has lived with misfortune for as long as he can remember, because the people around him keep dying tragically. He keeps even his childhood friend Akane at a distance. One evening at his favorite ramen shop, he meets Kuro, a girl with powers beyond those of an ordinary person. She is a Terra Guardian. Kuro tells him about Terra, a life energy linked to luck that is divided among three people who look exactly alike, and about the guardians who keep its balance while living in hidden tribes. Keita does not believe her until he is caught in the fighting of this secret world. Close to death, he forms a contract with Kuro without understanding what it truly means, and from then on he is bound to stay with her at all times. The result is a supernatural action series adapted from a manga by Korean creators Lim Dal-Young and Park Sung-Woo.