Isekai Mazoku Shoujo ga Iyasou ni Shinagara Shiri wo Sawattekure to Segandekuru Ken

Iyaran Kunai, a high school boy with a butt fetish, was about to be killed by a demon girl, but at the last second, he unleashes a move that’s way too lewd for her too handle!? This is a manga dedicated to ass-men everywhere—

(Source: Ganma!, translated)