The Warden of Grabon Castle

In order to restore her family's good name and position, Hyacinth agreed to become the warden of a remote castle. The oath is taken, the magical seals are put in place. However, it turns out that this gloomy place needs not a warden, but an overseer. And for the monster imprisoned on the border of worlds, she is now responsible with her head. Additionally, Hyacinth brought a secret with her to Grabon. And when it is revealed, there may be one more prisoner in the castle…