On her 16th birthday, Kanna Aoyagi is asked by her 28-year-old sister Yayoi to become an eroge seiyū (erotic game voice actress) at her sister's eroge company. Kanna disagrees at first, but after she thinks about all the things her sister has done for her she finally relents. But being a high school student and knowing nothing about eroge, can she do the job properly…