Oni Chichi Monogatari 
Noboru Tenkawa was despairing of this world. In the deep forest where he finally arrives, he meets a woman of indescribable beauty. While admiring her figure, he slips off a cliff and faints. When he woke up, he was attacked by horned women who took turns attacking him. Overwhelmed by the use of their hips and crushed by their huge breasts, this world was a boob heaven! And when the village chief, Dakki, breastfed him, Noboru's crotch did not deflate, but remained erect! He's filled with happiness at the Nyuuson celebration. 
 
(Source: Mediabank, translated)