The series follows Yahiro, who lives with his supposed younger sister, only to have his life turned upside down when a beautiful, busty princess named Maika Ou appears, also claiming to be his sister and moving in. [1, 3] Maika is initially bitchy and dominant, but Yahiro discovers she's secretly a submissive slut who craves his attention. [2] Their incestuous relationship quickly escalates into a series of intense sexual encounters. Yahiro relentlessly explores every inch of Maika's body, from her massive tits to her tight asshole, forcing her into increasingly degrading positions. [7] He fucks her raw, fills her holes with cum, and pushes her limits with anal sex, all while she protests weakly before succumbing to overwhelming pleasure. [7] The arc sees their dynamic shift from a tsundere act to pure carnal lust, with Yahiro taking complete control and using Maika as his personal fuck toy, their days filled with non-stop, depraved sex.