"Seimadaisen" is a prequel to the first Castle Fantasia. The events of the game takes place 500 years before those of "Castle Fantasia", and tells the story of a two hundred year long religious war between the Inshiera Empire and the Ruushiera Republic. The Empire worships the God of Light and considers the republicans followers of an evil god. The army of the empire has seven holy squads, and you command a knight named Hyuui, the leader of one of them. "Seimadaisen" is a strategy RPG with erotic content. You fight on large battle screens, navigating your party in turn-based mode, attacking when enemies are in range. Enemies drop hearts when defeated, and collecting those hearts can heal you and raise your parameters. Between battles, there are parts in which you'll have conversations with girls and will be able to choose different answers, leading to different endings.