A refined college girl fresh to Tokyo and unfamiliar with the chaos of crowded trains finds herself apologizing even when being groped. As she writhes, her slender yet busty silhouette becomes obvious. A middle-aged man watching her can't hold back anymore: "She's a hidden gem with incredible breasts!" In a situation where she can't cry out for help, her body begins to shake with an unknown pleasure. Her first taste of the city and her first forbidden encounter leave this pure girl hopelessly addicted to orgasms she never knew existed, making her wonder if she should keep commuting by train after all...