After his reincarnation from another world, Setsu leads a new life as a high school student. However, for an unknown reason, he is summoned back to the same world, Eclair. Before he can enjoy his return, he becomes embroiled in the war with the demons that he had originally ended. Though his old comrades rush to his aid, he also notices his old friend's magic on the battlefield. What is going on in the world of Eclair that Setsu enters for the second time?"