600 years ago, there existed a realm of powerful monsters called the Bakonauas. The Bakonauas tried to conquer the world. There are powerful warriors who are capable of protecting the world against them, the Lanzenreiter.
However, it was the year 905X, when all the Lanzenreiters suddenly disappeared. Nobody knew what had happened to them. Their whereabouts was shrouded in mystery and the whole world fell under the hands of the Bakonauas.