Yuya is excited to find out that Nanami, the "big sister" he has admired since childhood, is coming to his house for the first time in a long time. At first, he is nervous and can't speak well, but as they spend time alone, they gradually open up to each other... With the help of alcohol, he and Nanami share a kiss. Yuya is unable to contain his excitement at his first adult kiss, but Nanami is also unable to contain the throbbing in her body. Then, late at night, Nanami comes to Yuya's room...