On her 16th birthday, Himari Momochi inherits the mysterious 'Momochi House,' a mansion that ties her to her long-lost family. Unfazed by rumors of hauntings, Himari encounters Aoi Nanamori and his comrades squatting in her new abode. Despite their warnings to flee, Himari is determined to reclaim her home. However, she faces youkai attacks and discovers the mansion straddles the realms of the living and spirits. Shockingly, Aoi, not Himari, is the chosen guardian tethered to the house, losing his place in the mortal world. Refusing to abandon Aoi, Himari vows to undo his curse, embarking on a journey within the mansion's confines to free him from his ethereal chains.