[Flieger (Ten)] Seishokusha (english)

A high elf woman is captured as the test subject of a demon biologist's crossbreeding experiments—drugged, restrained by writhing tentacles, and chemically altered until her body can welcome any creature that wants to breed with her. Her captors observe with clinical amusement as she's mounted and used, her heavy breasts eventually swelling with milk until the minotaur specimen nurses directly from them. What the demon frames as pure reproductive research slowly strips away her resistance, leaving her transformed into something built to mother monsters.