Two years have passed since Wataru Ishibashi, an ordinary high-school student in modern-day Japan, visited the magic world of beautiful goddesses and rescued his girlfriend Mika. It seems he can now finally enjoy a peaceful time with his beloved girl. But one day, his old friend Ches, a cute cat-like fairy girl, appears in his room and summons him to the world of gods. It appears that Venus, the goddess of love, is in trouble due to the unforeseen events that have led to the outbreak of the Trojan war. Wataru is about to begin another adventure in the world of gods and ancient cultures.

Cal III is a Japanese-style adventure with visual novel characteristics. The player interacts with characters and is given several dialogue options or actions to choose from. There is no other interaction with the environment, and the progress is strictly linear. Most choices are optional, and only a few lead to Game Over. The computer versions of the game contain a few scenes with nudity, but overall the sexual content is by far milder than in the predecessors.