Can Rin save humanity? In the near future, a portal to [void] will appear somewhere in the world. Monsters crawl out of the portal and rampage. Humans create villages around [void] to keep them safe. Humans then use the monster's gene [red eye] to create a cyborg to thwart the monster's attack.

Twenty years later, the dormant [void] suddenly began to expand again. The main character, Rin, needs to investigate the cause behind her and save humanity from extinction. In the near future, a portal to [void] has opened somewhere in the world. Monsters are crawling out of the portal and rampaging. Humans have built [villages] around the radius of [void] to keep them safe.

Humans also used the monster's gene, the [red eye], to create cyborgs and thwart monster attacks. And 20 years have passed. The dormant [void] suddenly started to expand again. Our protagonist, Rin, needs to investigate the reasons behind her and save humanity from extinction.