The war against the demon lord forced humanity to use the arcaic magic arts to summon a hero from an alternative world. That hero turned out to be Kurohara Ichika, a teenager from modern day Japan. The hero defeated the demon lord and decided to live a quiet life growing papayas in the countryside with his wife and his son, Kurohara Noah. The legend was supposed to be over. However, one day young Noah gets run over by a carriage going at full speed, and turns out he will now be sent to the "real" world, the one where his father had come from, in an important mission with the fate of both worlds resting on his shoulders. Noah clearly doesn't like the idea, but knowing the basics of japanese common sense thanks to his dad, he thinks he won't have too much trouble finding his way in this parallel world. Or so it was supposed to be... "Wait, is this really Japan!?"