Parallel to our dimension is a world filled with magic, home to a host of mystical beings and fantastical powers. Humanity has learned to harness these forces and bring forth that world's entities to do their bidding through the power of 'summoners.' Fifteen years later, Kazuki Hayashizaki is chosen as the first male summoner. His attendance at an all-female summoner school, however, is met with opposition from his own sister, who is the school's most skilled swordsman. Can he overcome adversity and learn to become a first rate summoner?