Megachu!

Kousuke, a typical college student, experiences recurring nightmares of transforming into a destructive sex demon. While his daily life involves ordinary activities like playing video games, the reason for these dreams remains unclear. His routine is disrupted when the goddess Fauna appears, not to offer blessings but to eliminate him, as she identifies a dormant evil demon within him. Rather than destruction, Fauna adopts an alternative method to suppress the demonic power, engaging in extensive sexual activity with Kousuke alongside Jordh, her older sister and a creator of love potions. This plan is complicated by the interference of Natsuki, a minor devil who has her own designs for Kousuke. The narrative is derived from an adult game by Front Wing.