Since moving to Tokyo, her beloved younger brother has become cold and distant. She is worried that he may dislike her... Yuuka, a female college student with such worries, decides to try naked skinship! At first, the brother and sister are shy, but as they talk naked and openly, they close the distance in both body and Kokoro, and eventually cross the forbidden line... And the older sister writhes in pleasure and experiences the ultimate climax over and over again!