Helter Skelter Harudaku no Mura Vol. 1 ヘルタースケルタ

Miu is a university student. She has two sisters, Fubuki and Haruka, and their mother, Sayoko, is a famous fashion designer. One day, Sayoko receives a job offer from a tv production. That is to have a one-day trip to a spa hotel and they shoot it. She accepts the offer, and they visit a small village deep in the mountains. It seems there is a festival, and they get excited to take part in it. But, the festival actually features raping girls randomly for several days. They join it without knowing it....