MONSTER: Bouyoku no Sumu

Satoko, who lives with her parents-in-law, was worried about the presence of her brother-in-law. One day, Satoko was suddenly overwhelmed by her brother-in-law's giant body. Her brother-in-law, in the eyes of frightened Satoko, was just a sexual demon who devours women.
Although she hates her brother-in-law, every time she gets fucked, her body seeks out the pleasure.

(Source: GOT, translated)

Note: Published in COMIC Magnum Vol. 135∼144