Yukio Mimura, heir to the affluent Mimura family, inhabits the ancestral mansion with Reika Uehara, his partner in both romance and their shared vision of a tranquil life within the estate. Their stability crumbles upon the arrival of Hayato Mimura, a cousin asserting his right to seize the property. This clash stems from a generations-old pact forged by their fathers: a contest of psychological manipulation to decide inheritance through dominance.

Bound by the rules, Yukio and Hayato engage in a battle to erode Reika’s willpower, with the mansion as the ultimate reward. Yukio’s defiance is fueled by his resolve to protect Reika and their home, forcing him to navigate the contest’s treacherous demands while shielding their relationship from its corrosive tactics. The conflict positions him as both a guardian of their bond and an unwilling player in a legacy of familial rivalry, his actions balancing heartfelt loyalty against the cold strategies required to secure their future.