A nuclear attack has destroyed the world as we know it. The year is 2419. Japan is a dark and grim place ruled by demons. Once glorious, biggest cherry blossom tree is now dried. Lonely nephilim, Yuri Kinjo is humanity's only hope. Yuri finds the courage to start a secret revolutionary organization called The Dark Knights. The fight is jeopardized when Yuri is tricked by ruthless King of All Devils, Lord Rin Trotter, and injures her hand. Armed with swords and guns, The Dark Knights try their best to save mankind, but can they defeat tight-fisted demons and restore cherry blossom tree to its former glory?