Based on the erotic game by Speed. 
 
Kansen 2 (like the first episode) takes place during the initial outbreak of the Unknown virus epidemic, but the protagonists here have a much harder lot because they are stuck in the middle of a contaminated city immediately after its destruction by a mysterious cataclysm. 
 
Stalked by hordes of infected maniacs, Hiroshi Ookura and his friends seek safety inside a mostly intact shopping mall, but madness and death are everywhere... 
 
(Source: Visual Novel Database)

Kansen 2: Inzai Toshi