An uncle lives alone deep in the mountains... Kana and Mana look forward to going there every year because it's a great natural environment. However, in reality, the uncle and his mother have been paying off their debts with their bodies, without the young sisters' knowledge... Kana, the older sister, cannot understand the situation, but the uncle's habit of insulting her younger sister Mana with obscene words. Wanting to somehow help her sister and mother, Kana accepts the uncle's hopelessly disgusting sexual habits. However, gradually, that disgust... gradually begins to take control of Kana's body... and she begins to value herself more than her sister. More than her mother...