There is a shrine consacrated to the Goddess of Luck. One day, Kouji is pursued by Mizuki, his old friend/miko at the shrine, and hides himself in the shrine hall. When he looks around, he finds a statuette of a seal. He tries to touch it, but accidentally breaks it.... A Goddess (and her blue bird companion) suddenly comes out of the statuette and accidentally gives him an uncontrollable power of Luck which invites erotic things. The Goddess also loses all her power because of this accident and starts staying at his house. Various erotic things happen to him anytime, anywhere.... Lucky? Unlucky? Kouji's erotic life now begins...

[Edited from ErogeShop and English DLsite]