After graduating from university, Yura gets a job at a company and ends up having so much fun going to a drinking party that she misses the last train. She happened to know that her sister's house was nearby, so she called her and asked her to stay the night. However, her older sister and her husband are both working and seem to be busy lately, so they haven't had sex. The husband is in a state of frustration... and is lustful at Yura's defenseless appearance. Without asking any questions, she attacked her wife so that she wouldn't find out...