The Four Cardinal heroes, each armed with a sword, spear, bow or shield are ordinary men summoned from modern day Japan to defend the kingdom of Melromarc from a plague, Waves of Catastrophe that have ravaged the land for centuries. Naofumi Iwatani, an ordinary otaku is bestowed with only a measly shield. He joins with Malty Melromarc, the only person willing to train with him but is soon betrayed. He loses his standing with the kingdom and its people and begins his journey with a demi-human Raphtalia to strengthen himself and his reputation.