If There Was One City Left in the World

In 2708, humans were forced to be trapped in huge cities to resist the invasion of creatures from other worlds. A hundred years later, there was suddenly no news from the other three cities. The leaders in Kyushu decided to send an expedition team to three places to investigate. A year later, all the expedition team lost news, including Rikuo's parents... In 2815, Lu Sheng joined the spiritual realm organization and planned to embark on a journey to find his relatives... This is how it should be, but "Lu Sheng, I like you." The girl said to Lu Sheng.