When Kimihito Kurusu finds himself unexpectedly hosting a variety of monster girls due to an interspecies exchange program gone wrong, his once ordinary life takes a seductive turn. Tasked with caring for a charming Lamia named Miia, Kimihito becomes the center of attention for a growing harem of alluring and diverse monster girls. However, their amorous advances and desires are hindered by strict laws prohibiting inter-species romantic interactions. To navigate this legal obstacle, Kimihito explores the possibility of experimental marriages, delving into a world filled with creature-specific rules and complex interspecies dynamics. As his days unfold amidst a whirlwind of new arrivals and unpredictable events, Kimihito and his enchanting companions embark on a journey where the boundaries of love and desire are constantly tested.