The Demon Prince of Momochi House

Momochi-san Chi no Ayakashi Ouji (百千さん家のあやかし王子) or commonly known in English as The Demon Prince of the Momochi House, is a Japanese Manga series written and illustrated by Aya Shouoto.

Plot
On her sixteenth birthday, orphan Himari Momochi inherits her ancestral estate that she's never seen. Momochi House exists on the barrier between the human and spiritual realms, and Himari is meant to act as guardian between the two worlds. But on the day she moves in, she finds three handsome squatters already living in the house, and one seems to have already taken over her role!