While her husband's parents are away on a trip, Hina is tasked with caring for her step-grandfather, Masa-jii. But caring for an old-fashioned, dignified old man like Masa-jii is not as easy as it seems. Masa-jii takes advantage of Hina's Hina and demands erotic acts under the pretext of caring for her. Hina is at the mercy of Masa-jii's desires, and before long she is drawn to him not only physically but also Kokoro...