Sounds like the opening to an episode of The Twilight Zone: Japan. But this is not sci-fi. And as far as I know the late, great Rod Serling never visited Japan.
But he should have.
It's plausible to think that (a) since her bicycle looks like everyone else's bicycle, and (b) since there are about eleven thousand of them parked in theoretically perfect parallel fashion, she could grow old walking the aisles. That her bike is the one with the furry, marble-sized Hello Kitty thing hanging from the bell on her handlebars doesn't help because every other bicycle has a furry Hello Kitty thing too, even the boys' bicycles (another TZ: Japan episode).
Notice too that she is wearing a high school uniform. This is a solid indicator that her young mind is jam-packed with standardized test questions and answers to the point that she may even forget she has a bicycle. She would be saved, however, by the vague recollection that she has a furry marble-sized Hello Kitty thing hanging somewhere.
No, the reason she might never see her bicycle again is actually very simple (for Japan).