Red onis are alcoholic monster girls from Zipangu, who spend most of their time getting drunk in mountain caves. Their sex lives function in much the same way: red onis kidnap men, get them drunk, and rape them in a state of intoxication. The red onis often hang around with their blue cousins, who act as the brains of the drinking group.
A kind of Ogre called "Oni" that only inhabits the Zipangu region, distinguished by the horns growing from their forehead, and, as the name suggests, their bright red skin. Because of their superhuman strength, which lets them wield a huge metal rod with ease, the people of the surrounding areas fear them as monsters.
However, they are by no means ferocious. Although their speech and conduct are rough, they are bighearted and good-natured monsters that don't fret over minor details. They pay no heed whatsoever to the fact that humans fear them, and sometimes they are even pleased to receive men and sake as sacrificial offerings without even doing anything.
Their most favorite things are men and sake, and they always drink a lot. They're always drunk, which stains their red faces even redder. On rare occasions, they head to villages to acquire sake and human men that catch their interest to bring back with them to their dwellings. They'll sip sake together with the man they brought inside. After boozing it up and thoroughly enjoying themselves, they'll violently push over a man and enjoy violating him thoroughly, as if he were a snack to go along with the drinks.
And then, after copulating wildly again and again until they are satisfied, they once again resume drinking. According to them, it seems “the sake they drink after getting refreshed by doing it with a man tastes several times better than usual.” There is actually more to it than just their mood; the mana taken in from a man is said to enhance the deliciousness of sake. Were it the mana of a man they recognized as their husband, that would make it even more exceptional.
They are feared because it is said that “the men kidnapped are devoured, and they definitely are devoured, in a certain sense." Men that strike their fancy will be made their husbands, and will never be released by them again. These men will end up enjoying a feast of sake and flesh with them every day.
Other than that, men may also be brought along to drinking parties held by Zipangu monsters who are fond of drinking. At these parties, a man will be treated as the snack to go along with the drinks by the monsters gathered, and he will be ravished by them one after another. Whichever of the monsters takes a liking to the man will bring him home with her, and he will be made her husband. For that reason, most of the men kidnapped by red Oni do not return to their villages, and it's no wonder they are feared and such rumors are going around.
Additionally, among these Oni, there are said to be Oni of various colors each having different traits, such as “Blue Oni".