Teisou Gyakuten Sekai no Doutei Henkyou Ryoushu Kishi

Faust was brought up by his mother as a rare male knight after being reincarnated into a different universe where women rule and men's morals and chastity are inverted. He quickly becomes a war hero and achieves a lot, but because he carried over his mentality from his former world, he experiences daily pain in his groin when confronted with things like a Queen who is so poorly dressed that she could as well be naked or the sexual harassment of the wealthy Duchess he calls a friend, among other things.