Profound Desires of the Gods (Kamigami no fukaki yokubo)

An engineer from Tokyo travels to a remote island to supervise the development of a new railroad project. He encounters superstitious natives and discovers one family who has kept their son enslaved and in chains for 20 years for lusting after his sister. The man from Tokyo slowly becomes immersed in the culture and religion of the island to the point he no longer wishes to be part of modern civilisation. The brother escapes with his sister through the jungle before incurring the violent wrath of the outraged villagers. Years later, the train engineer believes he sees the dead sister on the train tracks, stopping the train but finding no trace of the girl or her brother. (All-Movie Guide, Dan Pavlides)