Sumire's sexual desire was so strong that her boyfriend asked her to break up with him. One day, when she was looking for something in her younger brother Katsuhiko's room, she found an unused shoulder ticket she had made for him a long time ago. When her parents were out on a trip and she was masturbating as much as she wanted, they found Katsuhiko outside her room, who was masturbating with himself. She remembers Sumire's shoulder slapping ticket, and she presents it to her as a ``vagina slapping ticket,'' which she hopes will help her use up the condom this time. While her parents were away, her siblings were able to share their sexual desires with each other.
