Probably between 2016 and 2019, I was looking through random manga on a run-of-the-mill scanlation website that I can't remember the name of, and that might not even exist any more. One manga that I came across was of the ecchi genre, but I think that it was of the more extreme kind of "ecchi" that bordered on being X-rated. I didn't read the manga at length but I did look through a few of the chapters. I don't think that it was a very long manga; its number of tankoubon volumes was probably in the single figures. From what I can remember, the story was about a young adult guy who lived alone, and one day suddenly became haunted by a girl who was some kind of spirit/ghost and looked to be the same age as the guy. I think that the girl had long hair and had an upbeat and possibly childish personality, but that's all that I can remember in detail about the main characters.
A later chapter I think was about how the girl character died young when she was a human, and there was a scene that showed her crying a lot. This part was possibly close to the end of the manga. As for the final chapter of the manga, I think that it involved the girl using some kind of power that she had, which caused every person in the vicinity, including in public, to engage in sexual activity.
It was a pretty bizarre and uncomfortable thing to see in a manga, but I'd still like to know exactly what this manga's name was.