My little sister is my sex practice partner! Asuka and I are bright and cheerful siblings who get along well. Recently, Asuka has found out that I'm still a virgin and makes fun of Asuka every time, which makes me a little angry, but she's cute when she sees me like that. Today, I have more time! Because I've got a girlfriend! Asuka is happy for me, but she starts to worry, wondering if I'm okay, and suddenly suggests, "Hey, you've never had sex before, right? Shall I teach you how to have sex?"