Dept. Heaven Episode IV.
The knight kingdom of Gleivnir with its twelve bands of knights had flourished long in the old castle of Aventheim.
The thousand-year-old Aventheim had been called impregnable, but all of a sudden King Willimgard was struck down by someone and his soul sealed away.
In their despair, the kingdom buried their sovereign, but his soul was stolen by the mysterious maiden Maria, and after that monsters appeared and destroyed the knight orders, capturing the castle.
Having evaded her knightly pursuers, Maria breaks the seal in the middle of the forest. The Wisp, the freed soul of the king, had neither will nor memory, but headed for Aventheim to seek its body.