A perverted insertion into an innocent-looking girl who happens to be riding a packed train! Taking advantage of the fact that she can't move or escape, he inserts his penis into her... but it would be a shame to do so, so he decides to insert it through her panties! The sensation of the penis pushing in is unbearable, and she becomes so aroused that her panties become stained! Her innocent body, heated with shame and pleasure, is not satisfied with just being penetrated through her panties, and she begins to ask for real insertion herself!