Since the description is pretty vague here's the premise: Protagonist got summoned to another world as a hero to fight against demons. He had no talent, so didn't achieve much. In the end humanity was wiped out and he dies. He suddenly finds him self in the past where he was summoned again, but the world has changed slightly. Men are uncommon (1 in 4) and women are typically stronger, thus leaders and soldiers. As consuming s**en makes women stronger (yang energy), male heroes purpose is to do s*xual acts... more>> with their female party members. The protagonist has a huge d*ck and high libido making him the best possible hero.

Based of the translated chapters I've read, it's an unremarkable smut series. World building is poor, characters are shallow and the s*x scenes are not sexy. Protagonist is generic, his big d*ck being his only notable trait. There doesn't seem to be any point to the regression as the knowledge hasn't been used at all, though that may change in future chapters. This isn't really a gender reverse role story, it's more just a male scarcity one. There are no big cultural differences, just h**ny women and men getting special treatment due to rarity. No real romance, protagonist gets oral from a women same day he met her and she suddenly become loyal to him due to his potential as hero (big d*ck and libido), agrees to marry him. There's a hilarious excuse for women being virg*ns, due to their magic power making their hymens too tough for weak men to penetrate.

Maybe it gets better, but I'm not invested enough to MTL it to find out. <<less