Long time ago, the races of humans and fairy creatures co-existed peacefully. But the power of magic corrupted some of them. The magic users were divided into those who supported the Light and those who turned to Darkness. The balance was broken, and peace between humans and fairy creatures were no longer possible. One day, a wandering samurai is caught in a storm on a sea; washed ashore, he loses his memory. Teaming up with two other warriors, the hero meets a benevolent sorceress named Garland, who sends them on a quest to rid the land of fairy creatures who got rampant, and help her in her battle against the evil sorceress whose plan is to destroy peace forever.

Like other Games Express titles, Hi-Leg Fantasy is an erotically-themed parody on a well-known game franchise - in this case, obviously the Final Fantasy series, most particularly its fifth installment. Combat, character growth, even menu design strongly remind of classic Final Fantasy games; as in those, the battles utilize the ATB (active time battle) system. The "job" system from Final Fantasy V is implemented here as well.

The adult element is present in the battles. Enemies are young and sexy girls, mostly fairy creatures of various kinds. As they sustain damage in battles, they begin to lose their clothes, until they become naked upon defeat.