Alex Harris, mid-twenties, is summoned to another world. In the summoning circle it is explained to him that he has been summoned to defeat the Demon King. During his status appraisal it is revealed that he has the "Futanari Harem Boost" that works like this: He can turn a woman into a futanari and add her to his harem. If he lets himself be fucked by one of the futanaris in his harem, all her skills are greatly boosted. The more women are in the harem the more the boost she gets after fucking him. Adding a woman to the harem will make both the woman and the protagonist fall in love. The protagonist must first fully explain the conditions to the woman he wants to add to the harem and she must consent.