'Yui' is 25 years old, in her second year of marriage. She boards a sleeper train from Sapporo heading for Ueno. The married woman has been sexless for the past year. Standing in the swaying carriage, she wriggles her hips and greedily enjoys sex. The married woman's libido shows no signs of waning but instead burns more intensely. In the morning shower room, she herself presses her body against him provocatively. In the moving confined space, the innocent married woman swallows the man in her lust…
