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.
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The Promised Neverland
Posuka Demizu, Kaiu Shirai
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Children of the Sea
Daisuke Igarashi
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Kuusou Garou
Kaori Minakami
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Attack on Titan
Hajime Isayama
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Sakasama no Patema: Another Side
Yasuhiro Yoshiura, toi8
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The Big O
Hajime Yatate, Hitoshi Ariga
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Black Bullet
Shiden Kanzaki, Morinohon
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Chrome Shelled Regios
Miyuu, Shuusuke Amagi
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Ergo Proxy: Centzon Hitchers and Undertaker
Yumiko Harao
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Princess Tutu
Mizuo Shinonome, Junichi Satou, Ikuko Ito