Meet Ichihashi Jirou, a sex drive scholar at St. Orgies' Private Academy. He decided to offer up his dick and semen for use in the Perversion Department's practicums in exchange for all sorts of perks. But as a virgin, he's very particular about who his very first partner will be.

Living right next door to Jirou is the Maezono household——a family of legendary perverts from the single mother to each of her four daughters. When the eldest Maezono daughter, Chihiro, catches Jirou masturbating one day, it isn't long before the entire household discovers that he's a virgin.

Now, an esteemed family of perverts like the Maezonos can't possibly stand by while a defenseless virgin like Jirou remains unmolested! Now that they've set their perverted sights on him...

...It's fuck or be fucked!

So Jirou decides he'll have his first time with one of the lovely Maezono ladies, but will that choice really be so simple?

[From Mangagamer]