Fault!!

This is the story of a boy, who became the lone Adam among four billion Eves. In a world where a pandemic has rendered all men impotent, high school student Itsuki is the exception who escaped it. In order to protect this secret, he transfers to a very special high school, which turns out to be composed of 90% girls! There, he encounters an upbeat and friendly senior, a sexually frustrated female teacher, a tomboyish school 'prince,' and an heiress from a wealthy family. For Itsuki, who has his pick of any woman in the world, the question remains: which one will he choose?

Narcotics Enforcement Agent Riko Ikazuchi is undercover with her junior colleague Noma in an apartment that serves as the hideout for a criminal organization. Despite Riko and Noma posing as a newlywed couple, the criminals begin to suspect them after not hearing any marital intimacy during the night. To convince them that they are a loving couple, Noma starts touching Riko's body...

One day, humanity was invaded by another world. Having experienced that battle, known as Other World War I, humanity moved to marine floats, built for emergency evacuation purposes, as soon as Other World War II began. It's around that time that Kizuna Hida is summoned by his elder sister and visits the Strategic Defense Academy Ataraxia where he meets Aine Chidorigafuchi, a girl who uses Heart Hybrid Gear Zeros to fight the otherworldly enemies. He has a tough time dealing with her, but when her Gear runs out of energy, the only way to get it back in action is to do something lewd to her!

The story takes place in Japan in the early 21st century, in an alternate reality where the Tokugawa Shogunate has remained in power. In this reality, student councils are tasked with oppressing schools. Yagyuu Muneakira is a high school student who rebels against his student council with the help of girls who've had the names of famous samurai heroes passed on to them.