Konatsu has begun to take an interest in sexual acts. Though petite, her large breasts are a worry. One night, on the last train, a man on board glances at her breasts, and Konatsu is happy that he is interested in them. She begins to flash her breasts every day, feeling excited. One day, when he notices her flashing them, she hides on the train and gives him a handjob. They even end up having sex sometimes... Still excited, the two get off the train and have sex at a hotel until the sun rises.