Make Princess not Conquest

It really speaks for itself, doesn't it? This will likely happen innumerable times throughout a playthrough of this game, but if you're going for speed then there are two options I find especially simple. First is the chapel outside the human kingdom just north of the Knights INC. guild, there are several nuns there who may offer to have sex with you should you speak to them, answer "sexy time" when prompted and you'll have your achievement. Even easier is the Knights INC. guild itself, there are typically some NPCs in there who are ready and willing to have sex with you should you ask. A few examples are a dog girl sitting at one of the tables and a goblin at the bottom left of the tavern where merchant princess sets up shop. Neither of these are givens though, as the NPC spawns are seemingly random and change by the day.