It is said that 70% of human brain capacity is unused. If human posses incredible power, it is strongly believed to be lying dormant within this region. This unused 70% brain capacity is known as "Night Head". The Kirihara brothers were abandoned by their parents because of their psychic powers. Since then they have lived in a laboratory within a barrier-protected forest. One day the barrier brakes and they manage to escape from the laboratory. Source: Baka-Updates Manga