This turned out to be an exceptional series. Really need a Knuckle Curve book with all their from "My Little Brother's Sex Ed Is Also Onee-chan's Duty, Right?" to this.
Another great work by Higenamuchi. Easily one of my top artist on Fakku.
Btw, pretty sure no one would complain if the gender roles were reversed. In fact, most seem to encourage these types of stories when it's the guy sleeping around.