Kikai Jikake no Marian

Psyluth Decker is a young English nobleman. Upon hearing the news of his father's death, he goes to the family mansion, a place surrounded by strange rumors, from which he tried to distance himself. Shortly after his arrival the young man notices that almost everyone he encounters has a secret, and becomes involved in a battle between powerful shapeshifters and mechanical creatures, aided by the trusty maid Marian.

[From Moby Games]