Kiss yori Amakute Fukai Mono

Are you happy now? Do you have someone to kiss? Have you ever been kissed? Have you ever kissed? I really like to kiss. Yuki loves to kiss. She not only kisses but also... has a boyfriend, but she has sex with someone else. One day, when she is having sex with her father, her younger sister sees them and says, "I wanna do it!" She is confused what to do... Not to mention her ex-boyfriend forcibly tries to have sex with her and her current boyfriend gets jealous. Her happy school life gradually breaks down...