(Edit later) [Background introduction: Due to a large-scale evolution event, Twin Cities, which was once a famous tourist destination in Zone 023, was slaughtered. After being attacked by mutated humans and mutated flora and fauna, these two cities remained desolate for a long time until ten years ago when the District Government decided to rebuild them and relocated a large population.]
[However, after the city was rebuilt, the residents inexplicably contracted an infectious disease that causes skin mutations, regression traits, weakness, and ultimately shortened life span. Due to the lack of effective prevention measures, these two cities still do not interact normally with other safe zones.]