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." Our world has never been the same.

Fifteen years later, Kazuki Hayashizaki is chosen as the first male summoner. His attendance in an all-female summoner class, however, is met with opposition-and none so strongly than from his own sister, the school's most skilled swordsman. As Kazuki is torn between the way of the sword and the world of summoning, can he overcome adversity and learn to harness his new powers?