A world where a huge castle suddenly appears. Inside the castle, which is shrouded in mystery, there are many creatures and treasures that are different from those of this world. The protagonist Rustil, who has no memory of the past, is drawn to the interior of the labyrinthine castle. The souls of heroes are floating around in the labyrinthine castle, and powerful abilities can be acquired from them. She also has the ability to control monsters. By capturing and training powerful monsters, she can use them as reliable companions.

A world where a huge castle suddenly appears. Inside the castle, which is shrouded in mystery, there are many creatures and treasures that are different from those of this world. The protagonist Rustil, who has no memory of the past, is drawn to the interior of the labyrinthine castle. The souls of heroes are floating around in the labyrinthine castle, and powerful abilities can be acquired from them. She also has the ability to control monsters. By capturing and training powerful monsters, she can use them as reliable companions.