My City in the Sky Is Too Great! It Can Upgrade Infinitely!

Gail had transmigrated to an era where everyone was building cities. Here, anybody could become the master of a city as long as they entered a world.
However, the city walls that he built looked a little strange compared to those of an ordinary city.
“Your city walls have awakened angel wings and can fly in the air.”
“Your Excalibur finds it too boring and slew the Giant Sky Dragon for fun.”
“Your city walls lack population and attracted countless females.”
Several years later, Gail looked in frustration at the countless females in his city, a little dumbfounded.
My city in the sky sure is great. It created the strongest harem for me.