Madness and unawakening sleep, Randolph syndrome. This new illness is slowly but steadily approaching humanity, caused by the huge underground world Asylum that appeared in Antarctica. There are strange creatures different from the earth, and unknown resources. People bet their lives on the depths of the mysterious new world to get huge wealth, organizational plots, or their own ambitions. And here alone, a young man with a wish in his heart is trying to challenge the front line of Asylum.
Episode 1
A strange disease is linked to a mysterious hole that leads to an underground world: the Asylum. "Sleepers" come to this world to fight strange monsters and retrieve unknown resources. Now, a young man who dreams of being a hero has arrived at the Asylum.
Episode 2
As Shigure begins to settle into his new life as a Sleeper, he begins to wonder what he is good at and what he can accomplish at the Asylum.
Episode 3
Larry goes on a dangerous and illegal mission deep in the Asylum and forces Shigure to go with him.
Episode 4
Shigure delves into XO Leslie's past when a mysterious assailant suddenly ambushes him.
Episode 5
Shigure is always embarrassed around Kobato and the rest of the team thinks he might have a crush on her. They hatch a plan to bring them together, but...
Episode 6
The day of the plan has arrived and the team heads towards the Asylum. But when Hayden shows up during the mission, things go terribly wrong.
Episode 7
With Leslie's death, the team is forced to find its way alone. And Shigure starts to have doubts about his mission...
Episode 8
With strong pressure from the command hierarchy, Vera decides to lead a mission to the Asylum on her own.
Episode 9
Vera is trapped in a time loop as she tries to complete her assassination mission. She reflects on the best way to make the mission successful.
Episode 10
Vera drives Shigure away from the platoon, but he's not ready to leave the Asylum... yet.
Episode 11
Now trapped in a time loop, Shigure struggles to unravel the mystery behind EL-Cee and Iceman's plans.
Episode 12
Shigure travels through time once more to save Vera and stop Iceman from destroying the world.
