Sixteen year-old Touma and his little sister Sana Tanaka have been forced from from their happy lives and dropped into a situation not befitting of children. Nobody knows anything as to why things are the way they are; not the police, not Touma, not anyone. However, Touma is determined to learn the reason for his and his sister's situation. Little does he know, a long path filled with hardships stands between him and the answers he seeks, and he will learn that this path cannot be traveled alone.