Involves a feminized guy turning into his older brother's "girlfriend." More specificially, his parents always wanted a girl, and the mom even had him crossdress as a kid because it was cute, while his older brother says he would be fine with marrying him if he was a girl like that. When he's an adult he refuses to crossdress though. So he accidentally takes a drug, sex follows, and when he calls Kei to complain he says, "It looks like the feminization experimental drug was effective. I gave it to your brother to give to you because if you turned into a girl, it wouldn't matter. After all your mom wanted a girl."
Predictably he's mad and says it's not alright with him. Kei adds that the drug will make you more sensitive. The chapter ends with him feeling the beginnings of lust again as his brother touches his head.