元勇者はモンスター娘に敗られたい（カドコミ）

Synopsis

Phil, the returned hero who defeated the Demon Queen fifteen years ago, had a wish... he wanted to be defeated by MONSTER GIRLS! Phil, a former hero, is now a forty-something-year-old adventurer...and he was still a virgin. Why? That was because he's only turned on by monster girls! Since he can't let anyone know about his fetish, he decided that he'll try to make it look like he's fighting with monster girls but be defeated by them. Succubus, slime, alraune (bewitching flower)... he loves all of them!!! If he was defeated, they would do dirty things to him like this and like that...that was something he'd been dreaming all his life. (source: global.bookwalker.jp)