All my class was summoned to a parallel world! Well, that’s what he thought, but Hikasa Eiji alone was left behind in his world. As he lamented the loss of his classmates, he was suddenly taken by a group in all-black outfits from a mysterious organization. They called themselves sorcerers; it was an organization set up to fight against interferences from parallel worlds. Eiji learned the truth from a member of the organization, Kuryuu Hisame, and decided he would help save her friends and childhood friend from the parallel world using his powers which he gained because of the summoning bug.