Kyokugen Dasshutsu Adv: Zennin Shibou Desu Prologue

This is the ONA/prologue for the game "Zero Escape: Virtue's Last Reward", the sequel to the game, "9 Hours 9 Persons 9 Doors".

With his last memory being that of his kidnapping, college student Sigma awakens to find himself trapped in a facility with eight strangers. The captives are soon informed that if they want to escape, they must play the "Nonary Game"—a complex contest of trust and betrayal, where deciding whom to believe in is the difference between life and death. To make matters worse, any initial trust between the players is tainted when they realize that the mastermind behind their predicament may be one of them...

(Source: MAL Rewrite)