Viper F40

Viper F40 is an instalment in the Viper series of interactive adult visual novels. Unlike the main Viper V series, Viper F40 contains only one story to play through. The game is fully-animated and has full Japanese voice acting. At certain points throughout the game, the player is prompted to choose a location where the current protagonist will visit.

The story follows two alternating protagonists, a police detective named Lilia and a private detective named Raika, as they work together to investigate the disappearances of three missing persons. The perpetrators respond to the investigation by kidnapping Seela, one of Lilia's colleagues, and sending Lilia a recording of her as a warning. Rather than back away, Lilia and Raika double down on their investigation, risking everything to solve the case.