The younger brother drinks depilatory cream he gets through mail-order, and it turns him into a girl. He still refuses to go outside, and the plot has the usual progression. The older brother comes home to find that his younger brother now sister has been experimenting with masturbating and sex toys, is attracted to her sleeping naked body and starts to masturbate himself. The younger sister wakes up, explains that experimentation is to be expected after changing sexes, remarks how it's great to have the potential for an unlimited number of orgasms, and then is really turned on by the older brother's cock and starts giving him head. They move on to anal sex (the older brother says it feels wrong to bust his younger brother's hymen, so the younger brother suggests anal sex in what gets called a "genius" move) before eventually the younger one enjoying it enough that she can't resist vaginal sex. Then in the last panel the younger brother turns back into a guy by drinking hair growth cream from the same mail order company. He probably shouldn't have drunk the medicine in the first place since it's the kind you rub on rather than ingest.