17 year old Ahn Injoo, the usual smart and innocent student from EunSung High School, would never be caught at a party of any sort... Until one night when her friend dragged her over...

A lot can happen in one night... And in three months is one of the consequences...

Three months later, after experiencing morning sickness and missed periods, Injoo finds out she's pregnant... With a baby in her belly and no clear memories of that one night, Injoo tries to search for the answer to her curious question... Who's the father...?