To Love Ru. It's a pretty famous harem manga with an MC named Rito. The first series was pretty vanilla, but the second series kept getting more and more lewd over time. The author has said there will be more, but it's been eight years and we haven't seen it yet.
You know that trope where the MC will trip or something, collide with a girl, and wind up with his hand on her chest? In To Love Ru the MC does that so much that the girls investigate him to see if he's cursed.
The author kept upping the ante because it was a running gag, with Rito winding up in more and more absurd positions (like his head literally in a girl's panties). It became a problem for the author because the gag couldn't really go any further without Rito actually impregnating every woman he ran into. I suspect it's part of the reason we haven't seen a third series yet.