Deep vaginal NTR: Five days a week, she has normal sex with her boyfriend, but the other two days are spent being NTR'd by his friend, who develops her cervix and cultivates her into a sexually deviant, large-breasted girlfriend. (Yami Rin FNS-110)

Boasting to her friend that she has sex with her girlfriend five days a week, Rin becomes the catalyst for an NTR story. Her friend, who has antisocial tendencies, thinks the remaining two days are a waste and simply wants to "enhance her sensitivity for two days a week, just for her sake." Rin is confused by her boyfriend's friend's outrageous behavior but accepts it anyway, and her cervix is penetrated, leading her to experience unprecedented vaginal orgasms…