In this episode—which is actually just straight-up hentai, let's be real—they changed the plot from the manga. In the manga, the sister wants to go all the way and sleep with him, but he stops and says they can't do it. That totally ruined the vibe for me in the manga. I thought it would be different here because of the scene where she’s all wet and showing skin, BUT NOPE, they had to go and screw it up here too.