My Secret Cache (1997)

Original title: ひみつの花園

Money makes it worth it.

Sakiko, a young bank teller, has an unhealthy obsession with money. Thieves hold up the bank, kidnapping Sakiko in the process, but eventually crash their car, resulting in a suitcase stuffed with cash falling into a nearby river. For the remainder of the film, Sakiko begins a desperate quest to retrieve the money.