I have been living with my girlfriend in Tokyo for four years. She has never thought about getting married, always working night shifts and coming home to sleep in the morning, so we haven't had sex for three months. The university entrance exam is coming up, and Hikari, my girlfriend's younger sister, came to Tokyo to take the exam and stayed at my place for a day. She is really beautiful, and she doesn't wear a bra, so when she saw my penis, it automatically got erect. While we were in the bathroom, there was an earthquake, and we were very close to each other, causing her to notice my erect penis pointing towards her. From that moment on, she started to seduce me, making me ejaculate inside her continuously. I knew she liked me, every time I talked about buying a house with my girlfriend, she would get upset. When she left, I realized that I wanted to be with her more, but she knew we shouldn't be together so she left. A few months later, my girlfriend and I got married, and she got into the university she desired. She wished me happiness, saying that the days she spent with me were the best time of her life...