Monarch of Gluttony: System of Sin - Chapter 2: 2: Curiosity is Gluttony!

Tang Zhen transmigrated to an apocalyptic world, where humans struggled to survive in various buildings that they built because the ground was covered in lethal dangers that were invisible to the naked eye. Tang Zhen transmigrated along with his mutated cell phone that was packed with miraculous applications.

There were all kinds of cities – some could fly in the sky, some could submerge into the ocean while some could become invisible – and shocking secrets were hidden within them.

The power of Tang Zhen’s city was…

He established a city and quickly leveled up his army with speeding tools. Then, he dominated this alternate world by seizing other cities.

He sat at the very top. Beneath his feet was a vast floating city guarded by dragons and surrounded by angels. Countless cannons were also set up at various corners of the city.

A million miles ahead, in the depths of the ocean, there was another city as large as a continent awaiting his conquest.

The world is terrorized by the powerful Black Witch who has been sealed in the moon. Every ten years, the night of Hexennacht arrives and a chosen witch must battle the Black Witch in hopes of finally defeating her.

As the current decade’s Hexennacht approaches, a mysterious girl named Kagami Kagami arrives and meets Horinouchi Mitsuru, the daughter of the previous Hexennacht representative.

It takes place between Kyoukai Senjou no Horizon and the City Series, two other series by the author.

A black pearl brought Jiang Feng from a doomsday stage where top masters with one emperor, two emperors, three emperors, four deities, and seven peerless cities show off their glory to parallel time and space, and this time and space-the end of the world has not yet opened! !! Under the sky, the youth look up, if I have strength, can I get through … these two time and space! !!

- Description from 69shu

This world has Fox Fairies, River Gods, Water Monsters, Great Demons and Cultivators who seek immortality.