Two high schools, one very timid and girly, the other slightly more open and adventurous, with a very attractive older sister. After realizing that his friend has a serious crush on his sister, he teases him, turning him on with his playful taunts, and the two get into a habit of masturbating together. The more adventurous one gets curious and takes things further, and both are caught by the sister.
Having his secret crush exposed by his would-be boy lover, the sister gets aroused and flattered and descends on him, and with a little coaxing, decides to drag her bi-curious brother into it.
