Years back, I read a harem webtoon. It was about a guy with ginger/red hair, he ended up purchasing a slave, she was a princess from another country. They had a certain contract that lead to them having to sleep with each other on full moons. He ended up saving other girls, and they join him. One specific thing that happened is that he and his slave were drugged at a residence they stayed at, and the people there tried to force him to sleep with the cursed princess there. In the end, he did it willingly, and she turned back into a Princess. I can’t remember what the title was, and I w really want to read it again. I’ve been thinking of it a lot lately.