A gauge is a special "power" passed down through the generations of specific bloodlines. However, less than 1% of the world have a gauge. In the country of Evare, those whom poses a gauge are used in the military to defend the country against enemies. In recent years however, those bloodlines that have gauge have been decreasing in rapid rates due to unknown reasonings. Will Saki, a normal human, find out what happened to his bloodline?