I think the game starts with the mc getting released from jail for selling drugs and the like. Turns out, after getting out from jail, he did not learn his lesson and he bought drugs from his friend. I believe this drug has some aphrodisiac effect and transformation. I think he gave some to his sister, making her into a nympho with tanned skin and big breats, etc. Obviously he has sex with her and the like. You have the choice to sell her to some otaku for money or something and other options. I do not think the game has much content so it was really just about the sister. I think the mc has tanned skin, muscular and tall. The art of the game, if I remember was stolen from a doujin game but I am not sure.