Long time ago, humans and succubi lived in harmony. Humans being weak needed the magical help of the succubi to raise monumental structures like pyramids and temples, but in exchange they needed to provide power to those creatures by mating with them. The humans gave them seed, the source of power for the succubi, but not all humans were equal - some of them were able to provide more power than others. Those people were called the Guardians, so to ensure balance and safety, the succubi created contracts that were used to bond spiritually a human and a succubus. However, a powerful succubus named Madhava couldn't stand the limitation of those contracts and had started a war.
In Bound by Lust you play as a young man ready to begin his life anew in the big city. Enjoy your new student life, increase your stats, build strong relationships with a vast cast of characters and discover the mysteries of a strange blue-skinned demon girl.