Danjohi ga Bukkowareta Sekai no Hito to Jinsei wo Koukanshimashita

A young man wasn’t popular at all for the three years of junior high school because of his stern face and huge physique. And after failing his entrance exams at the school he wanted to enroll in, it was decided that he would go to a boys’ school.

“At this rate, I’ll never be popular!”
『”Then, why don’t you exchange your life with a popular man’s?”』

A Goddess came before him, saying that Her favorite handsome man was too popular and in trouble, so She was looking for a man who wasn’t popular to exchange life with Her favorite. 

“Exchange life with a popular man’s life? There must be something behind it!”
『”Even if that’s the case, it’s better than being unpopular for your lifetime.”』
“Well, even if there’s inconvenient, I’ll get through it with my spirit and guts!”

The young man told the Goddess so and exchanged his life with a handsome man’s life… 

“Goddess! This isn’t Japan, isn’t it?!” 
『“So rude. This is Japan. Of a parallel world.”』

However, the young man then knew that the Parallel World had some problem, that was, an unbalanced gender ratio.

“If that’s the case, there’s no point in exchanging lives with a man in this world, rig…hm? this means…”

In a way, the heart of a woman who wasn’t popular couldn’t be understood in the true sense by a normal man there. 

“Am I the only man who understands the feelings of being unpopular?”

This was a story of a man in a harem-like environment, trying his best to make the girls in his surroundings happy.