Hirusagari no onna: chohatsu!

Natsuko Yashiro (aka Yujo Oribe) stars as Yuki, who picks up a gay hitchhiker after leaving her husband's house following an argument. When the hitchhiker discovers his boyfriend having sex with a woman, he decides to keep traveling with Yuki. They reach a diner, which is filled with scummy Deliverance rejects who proceed to rape and torture them for most of the film.