When Masami's father died, he was told by his grandfather that he had to move out. In order to find a new place that he could live in for 80,000 yen a month, he asked his unrequieted love "Kagome" to look for a new place for him. But unfortunately, because of that, he has had to join the "extremely normal phenomena observation society" that she founded. And on top if it, there are rumors that things seem to "appear" at the things that the she finds.

Enters childhood friends Mika and Reiko. Now they are both adult married women, and decided to vary their seemingly boring life with swing (partners swapping). Seas of enjoyment with topping of sweet secret drama.
Borderline story with walls of text.

From Imangascans:
Mahiro has two goals in life: first, to finally confess to his childhood friend who he loved for so long and second, to become a famous model. But there are various obstacles in Mahiro's path! For one thing, he dresses as a girl, named Hanabusu Arisu, when modeling. As if that wasn't enough, every woman in his vicinity gets the urge to spread her legs because of the special pheromone he emits! Will Mahiro ever come to confess his love to Miwa, or will he simply widen his harem and get engulfed in endless orgy?

Twenty-four-year-old Kirara is on her way to her wedding when she is killed in a car accident. However her love for her fiancé is so strong that she is permitted to return to earth as a ghost to see him. But she is sent back 8 years in time, to when she and her fiancé first met. However her own meddling in the past may make her 16 year-old-self turn away from her would-be fiancé.

Hiromi can't wait for her cousin Makoto to come live with her - but when "he" finally shows up, she gets a good deal more than she bargained for. Toshiki Yui turns a hentai fetish into the plot hook of this high school situation comedy.

18-year-old Mai Sugimoto is a college student starting this year. She was looking forward to the "college life," but she ends up living with two women because of a realtor's mistake. Furthermore, they are all 18-years-old and share the exact same name, Mai Suigimoto. Hence a life story of three Mai(s) full of fun and erotic excitement begins. Can these three girls get along?

One morning, upon waking up, people disappeared from the world. It seems only a single girl was left behind. A beautiful girl's sexual fantasy of seeking men and warmth.