Series A world where only I get erections

"What?! No way! Am I the only one in my class who gets erections? No, am I the only one in the world?!" It's been a year since all the other men stopped getting erections... but for some reason, I'm the only one who gets erections, and I've entered a period of incredible popularity!! Putting an end to the era where my female classmates were satisfied with just having lesbian encounters among themselves!!