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! Thanks to Himari's hard work, Aoi is able to remember his past and returns to his human form. While preparing a party to celebrate, Himari and Yukari discover that Aoi has a special connection with Himari's parents...