In the 21st century planet Earth was rendered inhospitable to life, and people mass-migrated to Planet Zi, the natural home of metallic life forms...

"Unknown" is a mysterious enemy that suddenly appeared a long time ago. As a countermeasure, the "Evolutionary Railway Development Agency" (ERDA) has...

A little bit in the future, the government has established a brand new organization with the purpose of rescuing lives to respond to the increasingly...