The Isolated Society
These manga feature a society that is physically isolated from the world. The populace might live inside of a walled or domed city or are limited to a small island. Typically, the society is unaware of what exists outside of their borders in the Outside World, or are forbidden to go there.
The Promised Neverland
Posuka Demizu, Kaiu Shirai
Children of the Sea
Daisuke Igarashi
Kuusou Garou
Kaori Minakami
Attack on Titan
Hajime Isayama
Sakasama no Patema: Another Side
Yasuhiro Yoshiura, toi8
The Big O
Hajime Yatate, Hitoshi Ariga
Black Bullet
Shiden Kanzaki, Morinohon
Chrome Shelled Regios
Miyuu, Shuusuke Amagi
Ergo Proxy: Centzon Hitchers and Undertaker
Yumiko Harao
Princess Tutu
Mizuo Shinonome, Junichi Satou, Ikuko Ito