In the past, humans conquered the Earth. That much is certain. But...

Masaki is the livestock of Chikyuu Ranch, the Oskyuu. He is a rare type of Gyuu, differing from the other breeders. One day, when he awoke, he found himself in an unfamiliar cage. Beyond the cage are the aliens who control the ranch! The Crimson Princess, the Princess's chamberlain, a boy who looks like a girl, and a slime who looks more like a girl?

For some reason, Masaki also had memories of being the only “Earthling” in Gyuu’s mind. On top of that, he was also a severe sci-fi otaku! A heterogeneous harem world, the dream of a heterochromatic sex maniac?!