Isekai where the MC is transported into a world where women go into heat. Even the most kindly of girls becomes ravenously randy. Girls knocking down doors to get to a man is not unheard of. Men have become extremely defensive and at times have to fight off a woman, which is now seen as kind of a rite of passage in adolescence. In fact it opens with him having to beat up a girl who is not taking no for an answer, and when he does he's horrified at what he has done only to turn and find the boys cheering for his first successful dick defense. And so it goes. Sometimes he goes along with a girl, sometimes he fights back. When he does, sometimes he wins and gets away, sometimes he loses and the girls have their way with him. Through it all he's still in love with the same girl from his home dimension, but struggles to come to terms with her because the sexual demands of her and every woman who gets her hands on him gets in the way.