An evil demon has emerged from the ruins of a sacred temple. A young woman named Erena is persecuted by the militant Hielun Empire, who pursues its own agenda and is convinced that Erena has a mysterious connection to the demon's powers. However, a knight named Vaice and his friends rescue Erena and prepare to defend her, gradually becoming involved in a large-scale armed conflict.

Kisō Louga is a turn-based strategy game. The gameplay consists entirely of battles, with anime-style cutscenes advancing the story between missions. The player navigates individual characters in an overhead locations. A contact with an enemy unit initiates a separate battle, where the player selects commands (Attack, Item, Special, etc.) from a menu.

Castles play an important role during battles: characters can retreat and heal in a player-controlled castle, and conquering an enemy castle is often required as well as part of the mission's objective. Castles may be defended by arches, catapults, etc., and their gates must be destroyed by attacking them. Missions often involve battles between multiple sides. Despite the RPG-like menus, individual statistics, and equipment management, there are no real role-playing elements in the game, since characters do not level up or become stronger in another fashion.