The stage is "Lagoon", a child-specific hydrophobic zone in a world that was destroyed by war.

The Mercenary Boy Kai who lives in the "Lagoon" utilizing the discontinued amusement park, meets one girl, Mio at a certain reason!
She is a clunky girl with silver hair and her mouth, and is a great at firing but cannot wrap a bandage.
So Kai knows the secrets of Mio. Mio continues to fight for dead body with a certain purpose.

Kai who layered her figure and makes Mio leave her home. Kai is a childhood familiar with the Dr.
The protagonist who enjoys some relief between the fleet in a crumbled world. But the fun days are not eternal.

Time Limit is so close to you