Amethyst

Intro Amethyst is an 18 year old female mage. You (you're a boy, sorry girls, you choose everything else about you) have been summoned to another world as the chosen hero by Amethyst to slay the Demon Queen, Cadence, who has nearly conquered all of this world. But you were summoned when you were in the shower and at the point of no return and your, ahem, "substance", came into contact with her as you appeared suddenly in front of her. In this world, girls coming into contact with the chosen hero's, ahem, "substance", makes the girls fall in love with the chosen hero immediately, makes them loyal to only the chosen hero, and gives the girls a temporary power boost.