He adopted to waking up in the body of a girl and being spontaneously fucked very quickly. Pretty sure he will end up in the body of his aunt and be fucked.
(Ch1) The MC's father was going to visit his sister in the mountains. His imouto didn't want to go, so the MC was stuck going with his father there. A short time after arriving, he's walking around the village when he hears noises and sees his aunt doing fellatio to some man.... oops its his father! (After reading Ch2, it's apparent from the speech style that his father and aunt swapped before doing that as well) MC keeps walking and meets a girl with a giant daikon radish who says his aunt sent her to show him around, but it turns out she is ALSO an aunt of the MC! ...She is his father's youngest sister (aged far apart, obviously)
They meet the weird alien guy whom she says his name, then tells the MC they should stop over in that shed first. After he enters, she says ominously not to worry, that it will be over quickly and the weird creature touches him and he passes out. Now swapped, she (predictably) becomes overwhelmed by lust immediately and comments on the MC making cute noises despite being a boy... maybe he's a natural? At which point the MC wakes up... confused and seeing himself, the stimulation overwhelmed him in the unfamiliar body and he comes already.