The mysterious, horny woman I was chatting with online and getting incredibly aroused turned out to be my older sister. (Nanami Tina ADN-539)

Yoshihiko's older sister, Nanami, was engaged to her boyfriend of many years, but the engagement was called off due to a certain incident... which revealed Nanami's secret sexual fetish. Heartbroken, Nanami eventually began secretly working part-time, utilizing her fetish...