This mansion is cursed. Underground there is a portal to hell. The former owner made a deal with the demon, thanks to which his family gained prosperity and power. All this is supported by human sacrifice. Now, more than a hundred years later, even his descendants are obliged to support this deal. Otherwise, the demon will take away all that he has given to people along with their lives. And he's always there.
You were an ordinary person, but due to lack of sleep and overwork, you were reborn "here", in another world similar to the middle ages, the youngest daughter of a duke. Your new family is fabulously rich, you have beautiful siblings and also caring parents. All of this is defined better than the life you had. Although the atmosphere in the mansion is strange and the servants are silent, but you turn a blind eye to it, not knowing that everyone here is afraid of someone.
You were walking around the garden looking at well-groomed roses until you saw a gardener's boy who was cutting roses with large garden scissors. The main rule of the estate, which every inhabitant of the mansion knows: "Never approach and do not talk to the gardener." But you didn't hear about it because it wasn't discussed in your presence.