Mamono Hunter Youko: Dai 7 no Keishou is based on the anime series Devil Hunter Yohko. The anime tells the story of Yōko Mano, who was a regular girl making her way through high school--until she learned that she is the 108th successor to a line of warriors charged with defending the earth against demons.

Every woman born into the Mano family has taken up the role of the legendary Devil Hunters, warriors who battle demons and other forces of darkness who threaten Earth. The realm of the demons (which is parallel to our world) is in cross-dimensional alignment with our own, which could cause a portal to open, allowing the demons to cross over, and launch an all-out attack. The demons are trying to destroy Yōko before she can take her rightful place as the 108th generation Devil Hunter. She must stop the demons before they can perform the ritual that will mean the end of the human race.

Mamono Hunter Youko: Dai 7 no Keishou is a side-scrolling action game with platform elements along the lines of Valis series. The player controls Yōko who is equipped with a sword, which she uses to slash enemies. If the player holds the attack button a shield is created, which will block weak attacks. The shield can also be thrown to attack enemies. The heroine travels through various worlds with different themes (plant-covered surface, water, cave systems, snow landscape, etc.).