12-year-old Ritsuka Aoyagi is, to say the least, a troubled child. Due to a rare case of psychological disorder, he has no memories of his life before the age of ten, and apparently is now the polar opposite of who he was before he lost his memories. This causes his mentally unstable mother to constantly abuse him, demanding that he leave and return the 'real' Ritsuka to her. For the past two years, his older brother Seimei had been the center of his life, protecting him from his mother and accepting and loving him. However, recently, Seimei was found burned to death in the classroom of Ritsuka's elementary school. Ritsuka is still in the process of recovering from what happened when he meets a man named Soubi, claiming to be Seimei's 'friend'. He informs Ritsuka that their name is "Loveless", and that he will be his Sacrifice - while Soubi is his "Fighter". Soon, Ritsuka finds himself in the midst a bizarre world where teams of two; the 'fighter' and 'sacrifice', combat each other using verbal spells. While treading through disturbing secrets and finding new friends within them, Soubi and Ritsuka bond, and through each other, begin to heal from the scars of their pasts.