Ryuu Kuroto and Rin Kurotsuki are what you may see as normal human brothers: sometimes bicker, care for each other, bicker a bit more. But one night 5 years ago, they realized they were something so much more: sons of the powerful and feared demon Shisai. Now, countless demons and evil spirits that seem to come from Japanese folklore are hunting them around the world, in every alley, every building, everywhere. How will these two brothers keep demons, ghosts, creatures, and the Vatican from killing them and all of Tokyo?!