One day, Yokota went to Oishi's house to hang out. He saw Oishi's mother, Saki, in her underwear. Her big pants covered her belly. Yokota was shocked by the unfashionable design. Her defenseless underwear, which was never meant to be seen, was much more vivid and erotic than the underwear of beautiful women he saw online. From that day on, Yokota started to visit Oishi's house at every opportunity and steal Saki's underwear. Before he knew it, he had come to believe that Saki was the only person he could give his virginity to.