Bloody Bug Mansion

(from ebookjapan):

Yu was adopted by the Omura family, an old family that was not blessed with children. Although it was deep in the lonely mountains, she began to live in a spacious and nicely decorated room. The horror began one night a few months later when she woke up to the sound of moaning echoing through the house. The gentle father became a sleepwalker, and the mother became violent, as if she had lost her mind.... After the unbelievable incident, the days became more and more difficult, and finally, the fear came to Yuu!