Set in 2142, Wonderful Days depicts a world that has been nearly destroyed by environmental pollution. Human life as we know it is almost extinct, and only a few were able to pull through the collapse of Earth's ecosystem. In order to deal with the chaos, a city named Ecoban was created. The city uses the very pollution that caused the disaster as an energy source. In this harsh new world, a social hierarchy has emerged, with an elite group of people in Ecoban believing themselves to be above the system. They are unwilling to accept survivors from outside the city unless they are put to work as laborers. Against this backdrop, a young man named Shua struggles to survive in the wasteland outside Ecoban. His life is made more difficult by his unrequited love for his childhood friend Jay, who may have feelings for the security commander Cade instead. As Shua navigates this complicated love triangle, he must also find a way to survive in a world that is barely habitable.