Owatatsumi Tatsuya was a normal teenage boy living a normal teenage life. And then...his life took an unexpected turn. A girl suddenly shows up in front of his house and claims that he is her betrothed in an arranged marriage! But this is not all. Suddenly, Tatsuya finds himself thrust into the mystical and unknown world of dragons--magical creatures who have existed for a very long time in a parallel world following a massive war between humans and dragons. What more, he is revealed to be the Dragonborn, a messiah who is prophesized to bring the war between humans and dragons to an end! Meanwhile, an ancient evil organization has made their move and plans to destroy the human realm once and for all, with their greatest enemy being the Dragonborn himself. Can Tatsuya survive this new world and satisfy the prophecy to bring peace to both realms? Or will he become victim to an ever increasing harem of princesses who try to claim his heart for their own?