Yuri and Mio, childhood friends and best friends who attend the same university, are on a trip to a mountain village in a certain prefecture. They stay at a trendy, stylish campsite and try to walk down the mountain instead of hiking, but they get lost in the unfamiliar mountains. As they wander, the two find a deserted guesthouse, but... There they find a den of beast-like men hungry for women. They attack the two young and healthy bodies, and several of their friends gang-rape them and impregnate them. Before long, Yuri and Mio's personalities collapse and they become masochistic females.