That interlude where she says she’s not actually an idiot always gets to me. Could just be an idiot unaware of their idiocy and then the rest of the hentai is as straightforward as it appears. Or, she really is smarter than she acts and the whole hentai is her cunning attempt to facilitate and perpetuate a hedonistic lifestyle with her brother. She wouldn’t need to be a true mastermind, just smart enough that the displayed level of retardation can be explained as “a long con to get with her brother” or something. Not sure which version is overall hotter, not that it matters.