When my parents asked my little sister, who is usually treated like a child, to "look after them while they're away," she must have developed a sense of responsibility, because even though she's seven years younger than me, she started acting like a mother, doing the housework, becoming very kind, and taking care of me in various ways. She even dresses in clothes that show her cleavage and panties, and is full of eroticism! When I got aroused by seeing that, she was surprised and said, "What a troublesome brother," but she was very happy and started devouring my erect cock!