After a cataclysm of unprecedented magnitude, the air has become unbreathable and hostile creatures have taken over the planet.
The last survivors have been forces to shelter as best they can in a tower. Among the survivors, volunteers are training to find a new Eden.
They are known as RIPPER !

While out on a reconnaissance mission, Oak Squad meets Junk, a young optimist who does not seem to have been affected by the state of the Earth...